@article{MTMT:34168012, title = {On Equilibria of Tetrahedra}, url = {https://m2.mtmt.hu/api/publication/34168012}, author = {Almádi, G. and MacG., Dawson R.J. and Domokos, Gábor and Regős, Krisztina}, doi = {10.1007/s00283-023-10294-2}, journal-iso = {MATH INTELL}, journal = {MATHEMATICAL INTELLIGENCER}, unique-id = {34168012}, issn = {0343-6993}, year = {2024}, eissn = {1866-7414}, orcid-numbers = {Regős, Krisztina/0000-0001-6866-2658} } @article{MTMT:34792456, title = {Dowker-type theorems for disk-polygons in normed planes}, url = {https://m2.mtmt.hu/api/publication/34792456}, author = {Basit, Bushra and Lángi, Zsolt}, doi = {10.1016/j.disc.2024.114019}, journal-iso = {DISCRETE MATH}, journal = {DISCRETE MATHEMATICS}, volume = {347}, unique-id = {34792456}, issn = {0012-365X}, year = {2024}, eissn = {1872-681X}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:34069754, title = {On monohedral tilings of a regular polygon}, url = {https://m2.mtmt.hu/api/publication/34069754}, author = {Basit, Bushra and Lángi, Zsolt}, doi = {10.1007/s00010-023-00973-y}, journal-iso = {AEQUATIONES MATH}, journal = {AEQUATIONES MATHEMATICAE}, volume = {98}, unique-id = {34069754}, issn = {0001-9054}, abstract = {A tiling of a topological disc by topological discs is called monohedral if all tiles are congruent. Maltby (J Comb Theory Ser A 66:40-52, 1994) characterized the monohedral tilings of a square by three topological discs. Kurusa et al. (Mediterr J Math 17:156, 2020) characterized the monohedral tilings of a circular disc by three topological discs. The aim of this note is to connect these two results by characterizing the monohedral tilings of any regular n-gon with at most three tiles for any n = 5.}, year = {2024}, eissn = {1420-8903}, pages = {535-555}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:34006049, title = {From the Separable Tammes Problem to Extremal Distributions of Great Circles in the Unit Sphere}, url = {https://m2.mtmt.hu/api/publication/34006049}, author = {Bezdek, Károly and Lángi, Zsolt}, doi = {10.1007/s00454-023-00509-w}, journal-iso = {DISCRETE COMPUT GEOM}, journal = {DISCRETE AND COMPUTATIONAL GEOMETRY}, unique-id = {34006049}, issn = {0179-5376}, abstract = {A family of spherical caps of the 2-dimensional unit sphere S-2 is called a totally separable packing in short, a TS-packing if any two spherical caps can be separated by a great circle which is disjoint from the interior of each spherical cap in the packing. The separable Tammes problem asks for the largest density of given number of congruent spherical caps forming a TS-packing in S-2. We solve this problem up to eight spherical caps and upper bound the density of any TS-packing of congruent spherical caps in terms of their angular radius. Based on this, we show that the centered separable kissing number of unit balls in Euclidean 3-space is 8. Furthermore, we prove bounds for the maximum of the smallest inradius of the cells of the tilings generated by n > 1 great circles in S-2. Next, we prove dual bounds for TS-coverings of S-2 by congruent spherical caps. Here a covering of S-2 by spherical caps is called a totally separable covering in short, a TS-covering if there exists a tiling generated by finitely many great circles of S-2 such that the cells of the tiling are covered by pairwise distinct spherical caps of the covering. Finally, we extend some of our bounds on TS-coverings to spherical spaces of dimension > 2.}, year = {2024}, eissn = {1432-0444}, orcid-numbers = {Bezdek, Károly/0000-0003-3097-0430; Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:34788249, title = {About Measuring the Stress Intensity Factor of Cracks in Curved, Brittle Shells}, url = {https://m2.mtmt.hu/api/publication/34788249}, author = {Cao, Siwen and Sipos, András Árpád}, doi = {10.3221/IGF-ESIS.69.01}, journal-iso = {FRATTURA INTEGR STRUTT}, journal = {FRATTURA ED INTEGRITA STRUTTURALE}, volume = {18}, unique-id = {34788249}, issn = {1971-8993}, abstract = {Most techniques of measuring the stress intensity factor (SIF) in the cracking process assume a crack in a planar medium. Currently, there is no effective approach for curved brittle shells, particularly for non-developable cases, i.e., shapes with non-vanishing Gaussian curvature. This paper introduces a novel approach to obtaining material properties related to fracture by experimentally observing weakly curved surfaces. Based on the DIC record of the displacement field around the crack tip, the truncated Williams expansion is fitted to the data adjusted according to the shallow shell equations. The convergence properties of the method are investigated by comparing experimental data of PMMA cylinders to theoretical and numerical predictions. The applicability of the technique to non-developable surfaces is verified. It is demonstrated that robust convergence requires the number of terms in the Williams expansion exceeding 6. For different geometries, the ratio of the data selection radius and the length of the crack should exceed 0.3.}, year = {2024}, pages = {1-17}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:33578682, title = {A discrete time evolution model for fracture networks}, url = {https://m2.mtmt.hu/api/publication/33578682}, author = {Domokos, Gábor and Regős, Krisztina}, doi = {10.1007/s10100-022-00838-w}, journal-iso = {CEJOR}, journal = {CENTRAL EUROPEAN JOURNAL OF OPERATIONS RESEARCH}, volume = {32}, unique-id = {33578682}, issn = {1435-246X}, abstract = {We examine geological crack patterns using the mean field theory of convex mosaics. We assign the pair \left({\overline{n } }^{*},{\overline{v } }^{*}\right) n ¯ ∗ , v ¯ ∗ of average corner degrees (Domokos et al. in A two-vertex theorem for normal tilings. Aequat Math https://doi.org/10.1007/s00010-022-00888-0 , 2022) to each crack pattern and we define two local, random evolutionary steps R 0 and R 1 , corresponding to secondary fracture and rearrangement of cracks, respectively. Random sequences of these steps result in trajectories on the \left({\overline{n } }^{*},{\overline{v } }^{*}\right) n ¯ ∗ , v ¯ ∗ plane. We prove the existence of limit points for several types of trajectories. Also, we prove that cell density \overline{\rho }= \frac{{\overline{v } }^{*}}{{\overline{n } }^{*}} ρ ¯ = v ¯ ∗ n ¯ ∗ increases monotonically under any admissible trajectory.}, year = {2024}, eissn = {1613-9178}, pages = {83-94}, orcid-numbers = {Regős, Krisztina/0000-0001-6866-2658} } @article{MTMT:34785837, title = {Numerical and experimental investigation on synthetic macrofiber-reinforced concrete manhole exposed to railway loads}, url = {https://m2.mtmt.hu/api/publication/34785837}, author = {Juhász, Károly Péter and Schaul, Péter and Veres, Boglárka}, doi = {10.1016/j.cscm.2024.e03093}, journal-iso = {CASE STUD CONSTR MAT}, journal = {Case Studies in Construction Materials}, volume = {20}, unique-id = {34785837}, issn = {2214-5095}, abstract = {The refurbishment of railway lines and the installation of new tracks necessitate the construction of numerous concrete manholes; therefore, the optimization of manholes should be investigated. To this end, the use of innovative materials in addition to advanced design methods with realistic modeling is required. In the case of conservatively designed structures, there exists the possibility of redesigning the structure utilizing suitable fiber-reinforced concrete (FRC) only. The main advantage of synthetic macrofibers over steel is their complete corrosion resistance, which is essential in corrosive environments. Other advantages include their low carbon footprint, reduced construction time, and cost-effectiveness. This paper outlines the optimization process for a conventional cast-in-situ concrete manhole. The imperative for a monolithic construction system stems from the diverse geometries and distinct designs of individual pipe culverts, compounded by the often-challenging accessibility of installation sites. In the optimization phase, synthetic macrofiber reinforcement replaced conventional reinforcing steel bars, using advanced finite element analysis (FEA). The design was not conducted on an equivalent basis, resulting in potential variations in the load-carrying capacity between reinforced concrete (RC) and FRC manholes. Nevertheless, both are deemed suitable for the specified loads. The conventional design method used for RC and the advanced finite element design method used for FRC were scrutinized, taking into account the existing standard environment. Subsequently, a real-scale test was conducted to validate the calculations. Carbon footprint analyses were performed for both the original and proposed solutions, and the results were compared. The solution obtained in this study is unique and pioneering in terms of both the calculation method and the structural design, and the CO2 calculations validate its necessity. © 2024 The Authors}, keywords = {numerical analysis; finite element method; Structural design; Corrosion resistance; Cost effectiveness; Carbon footprint; Optimisations; Fiber reinforced materials; Railroads; Design method; Numerical investigations; Footprint analysis; Reinforced concrete; Steel corrosion; steel fibers; fiber-reinforced concrete; Fiber-reinforced concretes; Railroad transportation; Carbon footprint analysis; manhole; real-scale test; Synthetic macrofiber; Carbon footprint analyse; Macrofibers; Manhole; Real scale tests; Synthetic macrofiber}, year = {2024}, eissn = {2214-5095} } @article{MTMT:34550819, title = {Morse–Smale complexes on convex polyhedra}, url = {https://m2.mtmt.hu/api/publication/34550819}, author = {Ludmány, Balázs and Lángi, Zsolt and Domokos, Gábor}, journal-iso = {PERIOD MATH HUNG}, journal = {PERIODICA MATHEMATICA HUNGARICA}, unique-id = {34550819}, issn = {0031-5303}, abstract = {Motivated by applications in geomorphology, the aim of this paper is to extend Morse–Smale theory from smooth functions to the radial distance function (measured from an internal point), defining a convex polyhedron in 3-dimensional Euclidean space. The resulting polyhedral Morse–Smale complex may be regarded, on one hand, as a generalization of the Morse–Smale complex of the smooth radial distance function defining a smooth, convex body, on the other hand, it could be also regarded as a generalization of the Morse–Smale complex of the piecewise linear parallel distance function (measured from a plane), defining a polyhedral surface. Beyond similarities, our paper also highlights the marked differences between these three problems and it also relates our theory to other methods. Our work includes the design, implementation and testing of an explicit algorithm computing the Morse–Smale complex on a convex polyhedron.}, year = {2024}, eissn = {1588-2829}, orcid-numbers = {Ludmány, Balázs/0000-0001-5373-7610; Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:34751447, title = {Effect of Bonding Type on the Failure of Reinforced Concrete Beam Strengthened with In-Situ High Performance Fibre Reinforced Concrete Layer}, url = {https://m2.mtmt.hu/api/publication/34751447}, author = {Nemessányi, Cecília and Pluzsik, Anikó}, doi = {10.1556/096.2024.00113}, journal-iso = {ÉPÍTÉS-ÉPÍTÉSZETTUDOMÁNY}, journal = {ÉPÍTÉS-ÉPÍTÉSZETTUDOMÁNY}, volume = {52}, unique-id = {34751447}, issn = {0013-9661}, abstract = {High performance fibre reinforced concrete (HPFRC) materials with tensile hardening behaviour can effectively be used for strengthening reinforced concrete beams. A perfect bond between the original and the reinforcing layer cannot be formed, the load-bearing capacity and ductility of the strengthened beam can significantly be affected by the interfacial bond strength between the contacting surfaces. In this paper, beam retrofitting with cast in-situ strengthening type is examined. The purpose of this experimental study is to investigate the impact of the different bond types on the load-bearing capacity, ductility, and failure mode of the strengthened beams in the case of cast in-situ strengthening. Twenty-four beam tests were performed with untreated and rough surfaced beams, with or without connecting elements. The effect of the bond type proved to be significant regarding the failure mode in the case of compression side strengthening, stronger bond resulted in higher load bearing capacity and ductility, too. When tensile side reinforcement was investigated no average increment was experienced in the maximal force and ductility due to the stronger bond. Based on the results, it can be concluded that the generally applied analytical models that assume perfect connection may lead to exaggerated results in the case of a compressed side HPC-strengthened beam. Therefore, it is necessary to develop a model that considers the effect of the imperfect bond. © 2024 The Authors.}, keywords = {beam; REINFORCEMENT; Strengthening; high performance fibre reinforced concrete}, year = {2024}, eissn = {1588-2764}, pages = {49-73} } @article{MTMT:34542705, title = {Many roads to success: Alternative routes to building an economic shell in land snails}, url = {https://m2.mtmt.hu/api/publication/34542705}, author = {Páll-Gergely, Barna and Sipos, András Árpád and Harzhauser, Mathias and Örstan, Aydın and Winkler, Viola and Neubauer, Thomas A}, doi = {10.1093/evolut/qpae018}, journal-iso = {EVOLUTION}, journal = {EVOLUTION}, volume = {78}, unique-id = {34542705}, issn = {0014-3820}, abstract = {Land snails exhibit an extraordinary variety of shell shapes. The way shells are constructed underlie biological and mechanical constraints that vary across gastropod clades. Here, we quantify shell geometry of the two largest groups, Stylommatophora and Cyclophoroidea, to assess the potential causes for variation in shell shape and its relative frequency. Based on µCT scans, we estimate material efficiency through 2D- and 3D-generalisations of the isoperimetric ratio, quantifying the ratios between area and perimeter of whorl cross-sections (2D) and shell volume and surface (3D), respectively. We find that stylommatophorans optimise material usage through whorl overlap, which may have promoted the diversification of flat-shelled species. Cyclophoroids are bound to a circular cross-section because of their operculum; flat shells are comparatively rare. Both groups show similar solutions for tall shells, where local geometry has a smaller effect because of the double overlap between previous and current whorls. Our results suggest that material efficiency is a driving factor in the selection of shell geometry. Essentially, the evolutionary success of Stylommatophora likely roots in their higher flexibility to produce an economic shell.}, year = {2024}, eissn = {1558-5646}, pages = {778-786}, orcid-numbers = {Páll-Gergely, Barna/0000-0002-6167-7221; Sipos, András Árpád/0000-0003-0440-2165; Neubauer, Thomas A/0000-0002-1398-9941} } @article{MTMT:34166610, title = {About the number of hinges at failure of semicircular and pointed masonry arches}, url = {https://m2.mtmt.hu/api/publication/34166610}, author = {Sipos, András Árpád}, doi = {10.1177/10812865231196796}, journal-iso = {MATH MECH SOLIDS}, journal = {MATHEMATICS AND MECHANICS OF SOLIDS}, unique-id = {34166610}, issn = {1081-2865}, abstract = {The collapse of masonry arches under static loads mainly occurs because some voussoir interfaces open and form hinges and eventually transform the structure into a mechanism. There is an interest in the maximum number of concurrent hinges at a given arch geometry and stereotomy, which latter refers to the cutting pattern of the voussoirs. This paper applies the governing equations of a geometrically exact rod to thrust line analysis while it adopts the Heymanian assumptions. With the new model, the number of concurrent hinges can be investigated in an organized and predictive manner generalizing the numerical and analytical results of the literature. Specifically, this paper proves that the number of hinges for a symmetric, circular pointed arch loaded by self-weight cannot exceed seven in the cases of vertical stereotomy and constant thickness in the vertical or normal directions. The maximum number of hinges is also seven for an arch with constant thickness and radial stereotomy.}, year = {2024}, eissn = {1741-3028}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:33665427, title = {An evolution model for polygonal tessellations as models for crack networks and other natural patterns}, url = {https://m2.mtmt.hu/api/publication/33665427}, author = {Bálint, Péter and Domokos, Gábor and Regős, Krisztina}, doi = {10.1007/s10955-023-03146-y}, journal-iso = {J STAT PHYS}, journal = {JOURNAL OF STATISTICAL PHYSICS}, volume = {190}, unique-id = {33665427}, issn = {0022-4715}, abstract = {We introduce and study a general framework for modeling the evolution of crack networks. The evolution steps are triggered by exponential clocks corresponding to local micro-events, and thus reflect the state of the pattern. In an appropriate simultaneous limit of pattern domain tending to infinity and time step tending to zero, a continuous time model, specifically a system of ODE is derived that describes the dynamics of averaged quantities. In comparison with the previous, discrete time model, studied recently by two of the present three authors, this approach has several advantages. In particular, the emergence of non-physical solutions characteristic to the discrete time model is ruled out in the relevant nonlinear version of the new model. We also comment on the possibilities of studying further types of pattern formation phenomena based on the introduced general framework.}, year = {2023}, eissn = {1572-9613}, orcid-numbers = {Regős, Krisztina/0000-0001-6866-2658} } @inproceedings{MTMT:34383912, title = {A Technique for the Measurement of the Morphological Evolution of Marine Pebbles}, url = {https://m2.mtmt.hu/api/publication/34383912}, author = {Bertoni, Duccio and Di Renzone, Gabriele and Domokos, Gábor and Favaretto, Chiara and Pozzebon, Alessandro and Sarti, Giovanni}, booktitle = {2023 IEEE International Workshop on Metrology for the Sea; Learning to Measure Sea Health Parameters (MetroSea)}, doi = {10.1109/MetroSea58055.2023.10317284}, unique-id = {34383912}, year = {2023}, pages = {433-438} } @article{MTMT:34108939, title = {Conway’s Spiral and a Discrete Gömböc with 21 Point Masses}, url = {https://m2.mtmt.hu/api/publication/34108939}, author = {Domokos, Gábor and Kovács, Flórián}, doi = {10.1080/00029890.2023.2241336}, journal-iso = {AM MATH MON}, journal = {AMERICAN MATHEMATICAL MONTHLY}, volume = {130}, unique-id = {34108939}, issn = {0002-9890}, year = {2023}, eissn = {1930-0972}, pages = {795-807}, orcid-numbers = {Kovács, Flórián/0000-0002-8374-8035} } @article{MTMT:33742876, title = {A characterization of the symmetry groups of mono-monostatic convex bodies}, url = {https://m2.mtmt.hu/api/publication/33742876}, author = {Domokos, Gábor and Lángi, Zsolt and Várkonyi, Péter László}, doi = {10.1007/s00605-023-01847-w}, journal-iso = {MONATSH MATH}, journal = {MONATSHEFTE FUR MATHEMATIK}, volume = {201}, unique-id = {33742876}, issn = {0026-9255}, abstract = {Answering a question of Conway and Guy (SIAM Rev. 11:78-82, 1969), Langi (Bull. Lond. Math. Soc. 54: 501-516, 2022) proved the existence of a monostable polyhedron with n-fold rotational symmetry for any n = 3, and arbitrarily close to a Euclidean ball. In this paper we strengthen this result by characterizing the possible symmetry groups of all mono-monostatic smooth convex bodies and convex polyhedra. Our result also answers a stronger version of the question of Conway and Guy, asked in the above paper of Langi.}, year = {2023}, eissn = {1436-5081}, pages = {703-724}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32864242, title = {A two-vertex theorem for normal tilings}, url = {https://m2.mtmt.hu/api/publication/32864242}, author = {Domokos, Gábor and G. Horváth, Ákos and Regős, Krisztina}, doi = {10.1007/s00010-022-00888-0}, journal-iso = {AEQUATIONES MATH}, journal = {AEQUATIONES MATHEMATICAE}, volume = {97}, unique-id = {32864242}, issn = {0001-9054}, year = {2023}, eissn = {1420-8903}, pages = {185-197}, orcid-numbers = {G. Horváth, Ákos/0000-0003-2371-4818; Regős, Krisztina/0000-0001-6866-2658} } @article{MTMT:34342487, title = {Size Effect of Synthetic Fibre Reinforced Concrete - Investigation using a Semi-Discrete Analytical Beam Model}, url = {https://m2.mtmt.hu/api/publication/34342487}, author = {Erdélyiné Tóth, Mária and Pluzsik, Anikó}, doi = {10.2478/acee-2023-0039}, journal-iso = {ARCHIT CIV ENG ENV}, journal = {ARCHITECTURE CIVIL ENGINEERING ENVIRONMENT}, volume = {16}, unique-id = {34342487}, issn = {1899-0142}, abstract = {The size effect is a well-known characteristic of concrete structures. However, in the case of fibre-reinforced concrete (FRC), this issue is not thoroughly explored. Most design recommendations of FRC neglect the size effect or handle the behaviour of FRC structures in case of different structural sizes similar to plain concrete structures (assuming FRC is a homogeneous material). The aim of this paper is to show that the size effect of FRC can be divided, the share of the concrete matrix and the fibres in the size-dependent properties is separable. For the size effect research fifteen synthetic macro fibre reinforced concrete and six plain concrete beam specimens were prepared and tested in three different sizes and then evaluated with the semi-discrete analytical (SDA) model. The analysis of the experimental specimens has shown that the size effect significantly influences the concrete material in the case of FRC with softening material behaviour, but the residual loadbearing capacity which mainly arise from the local bridging effect of fibres is essentially independent of the structural size. It is also shown in this paper that the two defining parameters of the SDA model is independent of the structural size, so the model provides an excellent tool in case of the design of real-sized FRC structures.}, keywords = {BEHAVIOR; strength; PRINCIPLES; Size effect; Fibre reinforced concrete; Analytical beam model; Synthetic fibre reinforcement}, year = {2023}, eissn = {2720-6947}, pages = {117-129} } @article{MTMT:34048901, title = {The Invisible Beauty of the Zeiss-Dywidag Domes: Topology Optimization of the Triangulated Rebar Grids}, url = {https://m2.mtmt.hu/api/publication/34048901}, author = {Gáspár, Orsolya and Kis, Alexandra E.}, doi = {10.1080/15583058.2023.2217659}, journal-iso = {INT J ARCHIT HERIT}, journal = {INTERNATIONAL JOURNAL OF ARCHITECTURAL HERITAGE}, unique-id = {34048901}, issn = {1558-3058}, abstract = {The Zeiss-Dywidag system was a pioneer in the history of thin concrete shells, which impacted and advanced theory and praxis worldwide. This study explains its relevance for the history of gridshells: the first ever built Zeiss-Dywidag dome started out as a geodesic gridshell, sprayed over by concrete. Walther Bauersfeld abandoned his own ingenious design for the first Planetarium in Jena in favour of a lamella-type topology for the equally self-bearing reinforcing grid of the later Zeiss-Dywidag domes. We reconstruct the optimization of the geometry and tessellation of the first built example of the latter, the Schott dome, and suggest possible motivations for the change. Bauersfeld's strikingly advanced theory of equivalent membrane shells, which played an essential role in the process, is published here for the first time. The significance of a unique benchmarking parameter, the so-called bar density (D-value), introduced by Bauersfeld is investigated. Its applicability to assess geometric fitness is assessed by a comparative study of selected grid topologies and geometries.}, keywords = {ARCHITECTURE; Topology optimization; Construction & Building Technology; Gridshell; lamella dome; bar density; equivalent membrane shell; geodesic domes; history of concrete shells; walther bauersfeld}, year = {2023}, eissn = {1558-3066} } @article{MTMT:32911089, title = {Multi-Hinge Failure Mechanisms of Masonry Arches Subject to Self-Weight as Derived from Minimum Thickness Analysis}, url = {https://m2.mtmt.hu/api/publication/32911089}, author = {Gáspár, Orsolya and Sajtos, István and Sipos, András Árpád}, doi = {10.1080/15583058.2022.2084702}, journal-iso = {INT J ARCHIT HERIT}, journal = {INTERNATIONAL JOURNAL OF ARCHITECTURAL HERITAGE}, volume = {17}, unique-id = {32911089}, issn = {1558-3058}, abstract = {The present study investigates the relation between the optimal geometry (quantified via the minimum thickness) and the number of concurrent hinges at the masonry arch’s limit state. The Heymanian assumptions regarding material behavior are adopted, and only constant thickness arches subject to static (i.e., self-weight) loading are considered. First, the only numerically verified completeness of the failure mode types (including 6 and even 7 hinges) of gothic arches is analytically proven. Next, it is investigated whether a higher number of hinges can concurrently occur for arbitrary, symmetric concave arches. A numerical procedure is presented which generates suitable arch geometries corresponding to a k-hinge mechanism, where k is an arbitrary odd integer not smaller than 5. For the generated class of arches, a higher number of concurrent hinges leads to lower minimum thickness values. However, it is explicitly proven that a higher number of hinges is not necessary for lower minimum thickness values. A small database about the geometry of the transversal arches of English and French medieval gothic cathedrals concludes the first part to allow comparison with the derived results. In the second part of the paper, existing literature results on the limit state analysis of gothic arches are extended by the effect of stereotomy on the failure mode type and minimum thickness value.}, year = {2023}, eissn = {1558-3066}, pages = {1921-1949}, orcid-numbers = {Gáspár, Orsolya/0000-0002-2123-1188; Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:34005757, title = {Form-finding using the Force Density Method: Existence of solutions, singularities, and an analogy to electric circuits}, url = {https://m2.mtmt.hu/api/publication/34005757}, author = {Guerra Riaño, Andres Felipe and Várkonyi, Péter László}, doi = {10.1177/09560599231207042}, journal-iso = {INT J SPACE STRUCT}, journal = {INTERNATIONAL JOURNAL OF SPACE STRUCTURES}, volume = {38}, unique-id = {34005757}, issn = {0956-0599}, abstract = {The Force Density Method is the oldest computational method for form-finding of funicular structures. The method is based on solving a linear system of equilibrium equations. Linearity ensures existence and uniqueness of the solution, provided that the coefficient matrix is non-singular. In the opposite case, the method often fails to deliver a feasible solution. In this study, we highlight a mathematical analogy between force density networks and electric circuits. Motivated by standard reduction steps in networks of electric resistors, inductors, or capacitors, we develop a new sequential reduction technique applicable to networks of force density elements. Network reduction enables analytic detection of singularity in many cases. Several examples illustrate the feasibility of the proposed singularity test, furthermore the role of singularities in classification of emergent structural forms is discussed.}, year = {2023}, pages = {302-326} } @book{MTMT:34129652, title = {Műegyetem - a történeti Campus / The historic Campus. A Budapesti Műszaki és Gazdaságtudományi Egyetem történeti Campusa / The historic Campus of the Budapest University of Technology and Economics}, url = {https://m2.mtmt.hu/api/publication/34129652}, isbn = {9789634217848}, author = {Gyetvainé Balogh, Ágnes and Frey, György Péter and Kalmár, Miklós and Kiss, Zsuzsanna Emília and Zsembery, Ákos}, editor = {Armuth, Miklós and Lőrinczi, Zsuzsa}, publisher = {Budapest University of Technology and Economics}, unique-id = {34129652}, year = {2023}, orcid-numbers = {Gyetvainé Balogh, Ágnes/0000-0002-2541-9356; Kiss, Zsuzsanna Emília/0000-0003-2143-7562} } @article{MTMT:33734944, title = {Isoperimetric problems for zonotopes}, url = {https://m2.mtmt.hu/api/publication/33734944}, author = {Joós, Antal and Lángi, Zsolt}, doi = {10.1112/mtk.12191}, journal-iso = {MATHEMATIKA}, journal = {MATHEMATIKA}, volume = {69}, unique-id = {33734944}, issn = {0025-5793}, abstract = {Shephard (Canad. J. Math. 26 (1974), 302-321) proved a decomposition theorem for zonotopes yielding a simple formula for their volume. In this note, we prove a generalization of this theorem yielding similar formulae for their intrinsic volumes. We use this result to investigate geometric extremum problems for zonotopes generated by a given number of segments. In particular, we solve isoperimetric problems for d-dimensional zonotopes generated by d or d+1$d+1$ segments, and give asymptotic estimates for the solutions of similar problems for zonotopes generated by sufficiently many segments. In addition, we present applications of our results to the l(1) polarization problem on the unit sphere and to a vector-valued Maclaurin inequality conjectured by Brazitikos and McIntyre in 2021.}, keywords = {APPROXIMATION; VOLUMES; POINTS; intrinsic volume; Zonotope; Isoperimetric problem; Mathematics, Applied; parallelotope; ball; rhombic dodecahedron; ZONOIDS}, year = {2023}, eissn = {2041-7942}, pages = {508-534}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32669283, title = {On generalized Minkowski arrangements}, url = {https://m2.mtmt.hu/api/publication/32669283}, author = {Kadlicskó, Máté and Lángi, Zsolt}, doi = {10.26493/1855-3974.2550.d96}, journal-iso = {ARS MATH CONTEMPOR}, journal = {ARS MATHEMATICA CONTEMPORANEA}, volume = {23}, unique-id = {32669283}, issn = {1855-3966}, abstract = {The concept of a Minkowski arrangement was introduced by Fejes Tóth in 1965 as a family of centrally symmetric convex bodies with the property that no member of the family contains the center of any other member in its interior. This notion was generalized by Fejes Tóth in 1967, who called a family of centrally symmetric convex bodies a generalized Minkowski arrangement of order μ for some 0 < μ < 1 if no member K of the family overlaps the homothetic copy of any other member K′ with ratio μ and with the same center as K′. In this note we prove a sharp upper bound on the total area of the elements of a generalized Minkowski arrangement of order μ of finitely many circular disks in the Euclidean plane. This result is a common generalization of a similar result of Fejes Tóth for Minkowski arrangements of circular disks, and a result of Böröczky and Szabó about the maximum density of a generalized Minkowski arrangement of circular disks in the plane. In addition, we give a sharp upper bound on the density of a generalized Minkowski arrangement of homothetic copies of a centrally symmetric convex body.}, year = {2023}, eissn = {1855-3974}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:33780709, title = {An automated neural network-based stage-specific malaria detection software using dimension reduction: The malaria microscopy classifier}, url = {https://m2.mtmt.hu/api/publication/33780709}, author = {Preißinger, Katharina and Kézsmárki, István and Török, János}, doi = {10.1016/j.mex.2023.102189}, journal-iso = {METHODSX}, journal = {METHODSX}, volume = {10}, unique-id = {33780709}, year = {2023}, eissn = {2215-0161} } @article{MTMT:33608779, title = {A New Insight into the Stability of Precariously Balanced Rocks}, url = {https://m2.mtmt.hu/api/publication/33608779}, author = {Ludmány, Balázs and Ignacio, Pérez-Rey and Domokos, Gábor and Mauro, Muñiz-Menéndez and Leandro R., Alejano and Sipos, András Árpád}, doi = {10.1007/s00603-023-03233-2}, journal-iso = {ROCK MECH ROCK ENG}, journal = {ROCK MECHANICS AND ROCK ENGINEERING}, volume = {56}, unique-id = {33608779}, issn = {0723-2632}, abstract = {Large granitic boulders resting on steep slopes represent considerable safety hazards that largely depend on the location of the contact surface characterized by the impression d , denoting the parallel distance between the contact surface and the original rock surface. On the other hand, this impression reflecting the often convex nature of the contact between boulders and resting platforms, cannot be measured precisely, so Factors of Safety (FoS) computed with this input may have significant uncertainties. Using geometric 3D analysis, here, we present the concept of computing FoS as a function of the impression d , admitting a much more reliable estimate of the actual hazards. Beyond introducing the FoS functions, we also identify all failure modes, some of which have not yet been investigated. We compute the FoS functions for the boulder Pena do Equilibrio , located in Spain. Our computations for FoS against sliding match all earlier results. However, we also compute FoS against toppling and against torsion and show that the latter may be critical. Since our methods are general, this suggests that torsion phenomena, which have been scarcely studied so far, may be relevant to analyze the stability of other natural rock boulders.}, year = {2023}, eissn = {1434-453X}, pages = {3539-3550}, orcid-numbers = {Ludmány, Balázs/0000-0001-5373-7610; Ignacio, Pérez-Rey/0000-0003-0883-7211; Domokos, Gábor/0000-0002-8676-6829; Mauro, Muñiz-Menéndez/0000-0001-5202-0044; Leandro R., Alejano/0000-0001-6540-2711; Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:34060364, title = {Fragmentation of inflated elastic brittle rings: Emergence of the quasi-equidistant spacing of cracks}, url = {https://m2.mtmt.hu/api/publication/34060364}, author = {Michel, Sébastien and Sipos, András Árpád}, doi = {10.1016/j.jmps.2023.105372}, journal-iso = {J MECH PHYS SOLIDS}, journal = {JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS}, volume = {179}, unique-id = {34060364}, issn = {0022-5096}, abstract = {The order of appearance and the position of meridional cracks in brittle domes is a delicate question of mechanics. This paper investigates a dimension-reduced model, a pressurized brittle ring constrained to the plane, to show that a simple, deterministic approach based on the Griffith theory of fracture predicts quasi-equidistant, i.e., close to an equal spacing of the emerging cracks. It is also demonstrated that the order of emergence is significantly affected by the variation of the in-plane elastic support as well the bending rigidity of the ring. In the model, the energy minimization is first recast into a sequence of coupled boundary value problems. The relationship between the mechanical model and geometric properties of the emerging pattern is studied numerically. The pattern is shown to be driven by elaborate co-dimension one bifurcations and by the requirement of global energy minimization.}, year = {2023}, eissn = {1873-4782}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:33771781, title = {The smallest mono-unstable convex polyhedron with point masses has 8 faces and 11 vertices}, url = {https://m2.mtmt.hu/api/publication/33771781}, author = {Papp, D and Regős, Krisztina and Domokos, Gábor and Bozóki, Sándor}, doi = {10.1016/j.ejor.2023.04.028}, journal-iso = {EJOR}, journal = {EUROPEAN JOURNAL OF OPERATIONAL RESEARCH}, volume = {310}, unique-id = {33771781}, issn = {0377-2217}, year = {2023}, eissn = {1872-6860}, pages = {511-517}, orcid-numbers = {Papp, D/0000-0003-4498-6417; Regős, Krisztina/0000-0001-6866-2658; Bozóki, Sándor/0000-0003-4170-4613} } @article{MTMT:33879799, title = {Polygonal tessellations as predictive models of molecular monolayers}, url = {https://m2.mtmt.hu/api/publication/33879799}, author = {Regős, Krisztina and Pawlak, R. and Wang, X. and Meyer, E. and Decurtins, S. and Domokos, Gábor and Novoselov, K.S. and Liu, S.-X. and Aschauer, U.}, doi = {10.1073/pnas.2300049120}, journal-iso = {P NATL ACAD SCI USA}, journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, volume = {120}, unique-id = {33879799}, issn = {0027-8424}, year = {2023}, eissn = {1091-6490}, orcid-numbers = {Regős, Krisztina/0000-0001-6866-2658} } @article{MTMT:34192919, title = {A simple model of edit activity in Wikipedia}, url = {https://m2.mtmt.hu/api/publication/34192919}, author = {Shimada, T. and Ogushi, F. and Török, János and Kertész, J. and Kaski, K.}, doi = {10.1016/j.physa.2023.129253}, journal-iso = {PHYSICA A}, journal = {PHYSICA A - STATISTICAL MECHANICS AND ITS APPLICATIONS}, volume = {630}, unique-id = {34192919}, issn = {0378-4371}, year = {2023}, eissn = {1873-2119} } @{MTMT:34163826, title = {On the number of congruent hinges of masonry arches at failure}, url = {https://m2.mtmt.hu/api/publication/34163826}, author = {Sipos, András Árpád}, booktitle = {HFSS 2023 : International Conference on Highly Flexible Slender Structures}, unique-id = {34163826}, year = {2023}, pages = {61-62}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @mastersthesis{MTMT:34034649, title = {Mechanikai és természeti formák elemzése: matematikai modellek a morfológiában}, url = {https://m2.mtmt.hu/api/publication/34034649}, author = {Sipos, András Árpád}, unique-id = {34034649}, year = {2023}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:34139844, title = {On the Buckling of the No-tension Material Masonry Column}, url = {https://m2.mtmt.hu/api/publication/34139844}, author = {Tajta, I. and Dulácska, Endre}, doi = {10.1556/096.2023.00095}, journal-iso = {ÉPÍTÉS-ÉPÍTÉSZETTUDOMÁNY}, journal = {ÉPÍTÉS-ÉPÍTÉSZETTUDOMÁNY}, volume = {51}, unique-id = {34139844}, issn = {0013-9661}, year = {2023}, eissn = {1588-2764}, pages = {181-194} } @article{MTMT:33721837, title = {Historical Shear Experiments of RC Beams in Hungary and their Effect on Change of Shear Design}, url = {https://m2.mtmt.hu/api/publication/33721837}, author = {Ther, Péter Pál and Sajtos, István}, doi = {10.3311/PPci.21433}, journal-iso = {PERIOD POLYTECH CIV ENG}, journal = {PERIODICA POLYTECHNICA-CIVIL ENGINEERING}, volume = {67}, unique-id = {33721837}, issn = {0553-6626}, abstract = {The shear behavior is one of the most mysterious physical phenomena of an RC (reinforced concrete) beam. Many shear-transfer actions (such as dowel action, cantilever action, aggregate interlock, tension softening, etc.) affect it. Still, there is no scientific agreement on the number and the role of these phenomena.The paper investigates the historical development of these shear-transfer actions and the calculation models made from them through the glass of experimental research in the last one and half centuries in Hungary, in the context of the current international state of the art. This historical approach gives us an understanding of how the researchers and engineers of the past tried to understand the structure, and it leads us to accept that we are also on the way to understanding the shear behavior. However, the perfect model and understanding are far away from now. But are we on the right way?}, keywords = {history; strength; Behavior Models; RC BEAMS; Shear behavior; REINFORCED-CONCRETE MEMBERS}, year = {2023}, eissn = {1587-3773}, pages = {647-658} } @article{MTMT:34434613, title = {An improved Lyapunov stability test of equilibria under frictional, unilateral contact by sums of squares programming}, url = {https://m2.mtmt.hu/api/publication/34434613}, author = {Várkonyi, Péter László}, doi = {10.1109/TAC.2023.3333738}, journal-iso = {IEEE T AUTOMAT CONTR}, journal = {IEEE TRANSACTIONS ON AUTOMATIC CONTROL}, unique-id = {34434613}, issn = {0018-9286}, year = {2023}, eissn = {1558-2523} } @{MTMT:34508337, title = {BME Látogató Központ}, url = {https://m2.mtmt.hu/api/publication/34508337}, author = {Armuth, Miklós and Takács, Lajos Gábor and Pataky, Rita and Sámson, Kinga and Sági, Gergely and Major, Zoltán and Müllner, Péter and Máthé, Dóra and Ferenczi, Natália and Kalmár, Péter and Hámornyik, József and Dr. Molnár, Bálint and Sütöri, Laura and Nemes, Bettina and Borbély, Áron and Faragó, Gergő and Dőry, Fruzsina and Fehér, Béla and Kelemen, László}, unique-id = {34508337}, abstract = {A tárlat a Műegyetem K épületének aulájából nyíló látogatótérben tekinthető meg. Az érdeklődők betekintést nyerhetnek a karok tevékenységébe, megismerhetik kutatási eredményeiket, valamint neves műegyetemisták találmányaival és BME-s relikviákkal is találkozhatnak.}, year = {2022} } @{MTMT:34504981, title = {Pecz Samu szobor talapzat , BME Központi Könytár}, url = {https://m2.mtmt.hu/api/publication/34504981}, unique-id = {34504981}, abstract = {Bodó Csaba, Pecz Samu szobor, talapzata}, year = {2022} } @article{MTMT:32282957, title = {An analogue of a theorem of Steinitz for ball polyhedra in R-3}, url = {https://m2.mtmt.hu/api/publication/32282957}, author = {Almohammad, Sami Mezal and Lángi, Zsolt and Naszódi, Márton}, doi = {10.1007/s00010-021-00815-9}, journal-iso = {AEQUATIONES MATH}, journal = {AEQUATIONES MATHEMATICAE}, volume = {96}, unique-id = {32282957}, issn = {0001-9054}, abstract = {Steinitz's theorem states that a graph G is the edge-graph of a 3-dimensional convex polyhedron if and only if, G is simple, plane and 3-connected. We prove an analogue of this theorem for ball polyhedra, that is, for intersections of finitely many unit balls in R-3.}, keywords = {Polyhedron; Steinitz's theorem; Ball polyhedron; Edge-graph}, year = {2022}, eissn = {1420-8903}, pages = {403-415}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343; Naszódi, Márton/0000-0002-4194-0205} } @article{MTMT:32900821, title = {The Nonsmooth Dynamics of Combined Slip and Spin Motion Under Dry Friction}, url = {https://m2.mtmt.hu/api/publication/32900821}, author = {Antali, Máté and Várkonyi, Péter László}, doi = {10.1007/s00332-022-09812-x}, journal-iso = {J NONLINEAR SCI}, journal = {JOURNAL OF NONLINEAR SCIENCE}, volume = {32}, unique-id = {32900821}, issn = {0938-8974}, year = {2022}, eissn = {1432-1467}, orcid-numbers = {Antali, Máté/0000-0001-6750-0710} } @CONFERENCE{MTMT:33547135, title = {Nonsmooth dynamics of slip and stick with a finite-sized contact area}, url = {https://m2.mtmt.hu/api/publication/33547135}, author = {Antali, Máté and Várkonyi, Péter László}, booktitle = {ENOC 2022: Book of abstracts}, unique-id = {33547135}, year = {2022}, pages = {557-558}, orcid-numbers = {Antali, Máté/0000-0001-6750-0710} } @article{MTMT:33561914, title = {Discrete isoperimetric problems in spaces of constant curvature}, url = {https://m2.mtmt.hu/api/publication/33561914}, author = {Basit, Bushra and Lángi, Zsolt}, doi = {10.1112/mtk.12175}, journal-iso = {MATHEMATIKA}, journal = {MATHEMATIKA}, volume = {69}, unique-id = {33561914}, issn = {0025-5793}, abstract = {The aim of this paper is to prove isoperimetric inequalities for simplices and polytopes with d+2$d+2$ vertices in Euclidean, spherical and hyperbolic d-space. In particular, we find the minimal volume d-dimensional hyperbolic simplices and spherical tetrahedra of a given inradius. Furthermore, we investigate the properties of maximal volume spherical and hyperbolic polytopes with d+2$d+2$ vertices with a given circumradius, and the hyperbolic polytopes with d+2$d+2$ vertices with a given inradius and having a minimal volume or minimal total edge length. Finally, for any 1 <= k <= d$1 \leqslant k \leqslant d$, we investigate the properties of Euclidean simplices and polytopes with d+2$d+2$ vertices having a fixed inradius and a minimal volume of its k-skeleton. The main tool of our investigation is Euclidean, spherical and hyperbolic Steiner symmetrization.}, year = {2022}, eissn = {2041-7942}, pages = {33-50}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32517495, title = {On k-diametral point configurations in Minkowski spaces}, url = {https://m2.mtmt.hu/api/publication/32517495}, author = {Bezdek, Károly and Lángi, Zsolt}, doi = {10.1016/j.disc.2021.112700}, journal-iso = {DISCRETE MATH}, journal = {DISCRETE MATHEMATICS}, volume = {345}, unique-id = {32517495}, issn = {0012-365X}, abstract = {The structure of k-diametral point configurations in Minkowski d-space is shown to be closely related to the properties of k-antipodal point configurations in Rd. In particular, the maximum size of k-diametral point configurations of Minkowski d-spaces is obtained for given k >= 2 and d >= 2 generalizing Petty's results (Petty, 1971 [24]) on equilateral sets in Minkowski spaces. Furthermore, bounds are derived for the maximum size of k-diametral point configurations in given Minkowski d-space (resp., Euclidean d-space). Some of these results have analogues for point sets, which are discussed as well. In the proofs convexity methods are combined with volumetric estimates and combinatorial properties of diameter graphs. (C) 2021 Elsevier B.V. All rights reserved.}, year = {2022}, eissn = {1872-681X}, orcid-numbers = {Bezdek, Károly/0000-0003-3097-0430; Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32461660, title = {Mono-unstable polyhedra with point masses have at least 8 vertices}, url = {https://m2.mtmt.hu/api/publication/32461660}, author = {Bozóki, Sándor and Domokos, Gábor and Kovács, Flórián and Regős, Krisztina}, doi = {10.1016/j.ijsolstr.2021.111276}, journal-iso = {INT J SOLIDS STRUCT}, journal = {INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, volume = {234-235}, unique-id = {32461660}, issn = {0020-7683}, year = {2022}, eissn = {1879-2146}, orcid-numbers = {Bozóki, Sándor/0000-0003-4170-4613; Kovács, Flórián/0000-0002-8374-8035; Regős, Krisztina/0000-0001-6866-2658} } @article{MTMT:32481039, title = {Cracking patterns of brittle hemispherical domes: an experimental study}, url = {https://m2.mtmt.hu/api/publication/32481039}, author = {Cao, Siwen and Sipos, András Árpád}, doi = {10.3221/IGF-ESIS.59.20}, journal-iso = {FRATTURA INTEGR STRUTT}, journal = {FRATTURA ED INTEGRITA STRUTTURALE}, volume = {16}, unique-id = {32481039}, issn = {1971-8993}, abstract = {Crack formation in hemispherical domes is a distinguished problem in structural mechanics. The safety of cracked domes has a long track record; the evolution of the cracking pattern received less attention. Here, we report displacement-controlled loading tests of brittle hemispherical dome specimens, including the evolution of the meridional cracking pattern. The 27 investigated specimens, 20 cm in diameter, were prepared in 3D printed molds, and their material is one of the three mixtures of gypsum and cement. We find that neither the (limited) tensile strength nor the exact value of the thickness significantly affects the statistical description of the cracking pattern, i.e., the cracking phenomenon is robust. The maximal number of the meridional cracks never exceeds seven before the fragments’ disintegration (collapse). We find that the size distribution of the fragments exhibits a lognormal distribution. The evolution is reflected in the load-displacement diagrams recorded in the test, too, as significant drops in the force are accompanied by an emergence of one or more new cracks, reflecting the brittle nature of the phenomenon. A simple, stochastic fragmentation model, in which a segment is fragmented at either in the middle or at the fourth point, fairly recovers the observed size distribution.}, year = {2022}, pages = {265-310}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:31009246, title = {On Some Average Properties of Convex Mosaics}, url = {https://m2.mtmt.hu/api/publication/31009246}, author = {Domokos, Gábor and Lángi, Zsolt}, doi = {10.1080/10586458.2019.1691090}, journal-iso = {EXP MATH}, journal = {EXPERIMENTAL MATHEMATICS}, volume = {31}, unique-id = {31009246}, issn = {1058-6458}, abstract = {In a convex mosaic in we denote the average number of vertices of a cell by and the average number of cells meeting at a node by Except for the d = 2 planar case, there is no known formula prohibiting points in any range of the plane (except for the unphysical strips). Nevertheless, in d = 3 dimensions if we plot the 28 points corresponding to convex uniform honeycombs, the 28 points corresponding to their duals and the 3 points corresponding to Poisson-Voronoi, Poisson-Delaunay and random hyperplane mosaics, then these points appear to accumulate on a narrow strip of the plane. To explore this phenomenon we introduce the harmonic degree of a d-dimensional mosaic. We show that the observed narrow strip on the plane corresponds to a narrow range of We prove that for every there exists a convex mosaic with harmonic degree and we conjecture that there exist no d-dimensional mosaic outside this range. We also show that the harmonic degree has deeper geometric interpretations. In particular, in case of Euclidean mosaics it is related to the average of the sum of vertex angles and their polars, and in case of 2 D mosaics, it is related to the average excess angle.}, year = {2022}, eissn = {1944-950X}, pages = {783-793}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:30808711, title = {Natural Numbers, Natural Shapes}, url = {https://m2.mtmt.hu/api/publication/30808711}, author = {Domokos, Gábor}, doi = {10.1007/s10516-018-9411-5}, journal-iso = {AXIOMATHES}, journal = {AXIOMATHES}, volume = {32}, unique-id = {30808711}, issn = {1122-1151}, abstract = {We explain the general significance of integer-based descriptors for natural shapes and show that the evolution of two such descriptors, called mechanical descriptors (the number N(t) of static balance points and the Morse–Smale graph associated with the scalar distance function measured from the center of mass) appear to capture (unlike classical geophysical shape descriptors) one of our most fundamental intuitions about natural abrasion: shapes get monotonically simplified in this process. Thus mechanical descriptors help to establish a correlation between subjective and objective descriptors of perceived objects.}, year = {2022}, eissn = {1572-8390}, pages = {743-763} } @article{MTMT:30799093, title = {Plato’s Error and a Mean Field Formula for Convex Mosaics}, url = {https://m2.mtmt.hu/api/publication/30799093}, author = {Domokos, Gábor and Lángi, Zsolt}, doi = {10.1007/s10516-019-09455-w}, journal-iso = {AXIOMATHES}, journal = {AXIOMATHES}, volume = {32}, unique-id = {30799093}, issn = {1122-1151}, abstract = {Plato claimed that the regular solids are the building blocks of all matter. His views, commonly referred to as the geometric atomistic model, had enormous impact on human thought despite the fact that four of the five Platonic solids can not fill space without gaps. In this paper we quantify these gaps, showing that the errors in Plato’s estimates were quite small. We also develop a mean field approximation to convex honeycombs using a generalized version of Plato’s idea. This approximation not only admits to view convex mosaics in d=3 dimensions as a continuum but we also find that it is quite accurate, showing that Plato’s geometric intuition may have been remarkable.}, year = {2022}, eissn = {1572-8390}, pages = {889-905}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:30548681, title = {Tracking Critical Points on Evolving Curves and Surfaces}, url = {https://m2.mtmt.hu/api/publication/30548681}, author = {Domokos, Gábor and Lángi, Zsolt and Sipos, András Árpád}, doi = {10.1080/10586458.2018.1556136}, journal-iso = {EXP MATH}, journal = {EXPERIMENTAL MATHEMATICS}, volume = {31}, unique-id = {30548681}, issn = {1058-6458}, abstract = {In recent years it became apparent that geophysical abrasion can be well characterized by the time evolution N(t) of the number N of static balance points of the abrading particle. Static balance points correspond to the critical points of the particle's surface represented as a scalar distance function r, measured from the center of mass of the particle, so their time evolution can be expressed as N (r (t)) . The mathematical model of the particle can be constructed on two scales: on the macro (global) scale the particle may be viewed as a smooth, convex manifold described by the smooth distance function r with N = N (r) equilibria, while on the micro (local) scale the particle's natural model is a finely discretized, convex polyhedral approximation r(Delta) of r, with N-Delta = N(r(Delta)) equilibria. There is strong intuitive evidence suggesting that under some particular evolution models (e.g., curvature-driven flows) N(t) and N (Delta)(t) primarily evolve in the opposite manner (i.e. if one is increasing then the other is decreasing and vice versa). This observation appears to be a key factor in tracking geophysical abrasion. Here we create the mathematical framework necessary to understand these phenomena more broadly, regardless of the particular evolution equation. We study micro and macro events in one-parameter families of curves and surfaces, corresponding to bifurcations triggering the jumps in N(t) and N (Delta)(t). Based on this analysis we show that the intuitive picture developed for curvature-driven flows is not only correct, it has universal validity, as long as the evolving surface r is smooth. In this case, bifurcations associated with r and r (Delta) are coupled to some extent: resonance-like phenomena in N (Delta)(t) can be used to forecast downward jumps in N(t) (but not upward jumps). Beyond proving rigorous results in the case of evolving planar curves for the Delta -> 0 limit on the nontrivial interplay between singularities in the discrete and continuum approximations we also show that our mathematical model is structurally stable. This property serves as the basis for the second, experimental part of our research where we demonstrate via computer simulations that the phenomena on evolving surfaces appear to be closely analogous to the planar case, however, they also show additional geometric features which are still not completely understood.}, year = {2022}, eissn = {1944-950X}, pages = {1-20}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343; Sipos, András Árpád/0000-0003-0440-2165} } @book{MTMT:33704751, title = {DUILI 90}, url = {https://m2.mtmt.hu/api/publication/33704751}, isbn = {9786158196536}, editor = {Dubniczky, Miklós and Hegyi, Dezső}, publisher = {Magyar Mérnöki Kamara Tartószerkezeti Tagozat}, unique-id = {33704751}, year = {2022} } @article{MTMT:33093510, title = {Fully spherical 3D datasets on sedimentary particles: Fast measurement and evaluation}, url = {https://m2.mtmt.hu/api/publication/33093510}, author = {Fehér, Eszter and Havasi-Tóth, Balázs and Ludmány, Balázs}, doi = {10.1556/24.2022.00124}, journal-iso = {CENT EUR GEOL}, journal = {CENTRAL EUROPEAN GEOLOGY}, volume = {65}, unique-id = {33093510}, issn = {1788-2281}, abstract = {Recently it became increasingly evident that the statistical distributions of size and shape descriptors of sedimentary particles reveal crucial information on their evolution and may even carry the fingerprints of their provenance as fragments. However, to unlock this trove of information, measurement of traditional geophysical shape descriptors (mostly detectable on 2D projections) is not sufficient; fully spherical 3D imaging and mathematical algorithms suitable to extract new types of inherently 3D shape descriptors are necessary. Available 3D imaging technologies force users to choose either speed or full sphericity. Only partial morphological information can be extracted in the absence of the latter (e.g., LIDAR imaging). In the case of fully spherical imaging, speed was proved to be prohibitive for obtaining meaningful statistical samples, and inherently 3D shape descriptors were not extracted. Here we present a new method by complementing a commercial, portable 3D scanner with simple hardware to quickly obtain fully spherical 3D datasets from large collections of sedimentary particles. We also present software for the automated extraction of 3D shapes and automated measurement of inherently 3D-shape properties. This technique allows for examining large samples without the need for transportation or storage of the samples, and it may also facilitate the collaboration of geographically distant research groups. We validated our software on a large sample of pebbles by comparing previously hand-measured parameters with the results of automated shape analysis. We also tested our hardware and software tools on a large pebble sample in Kawakawa Bay, New Zealand.}, year = {2022}, eissn = {1789-3348}, pages = {111-121}, orcid-numbers = {Fehér, Eszter/0000-0002-4022-7221; Ludmány, Balázs/0000-0001-5373-7610} } @article{MTMT:33078387, title = {Volume of the Minkowski sums of star-shaped sets}, url = {https://m2.mtmt.hu/api/publication/33078387}, author = {Fradelizi, Matthieu and Lángi, Zsolt and Zvavitch, Artem}, doi = {10.1090/bproc/97}, journal-iso = {PROC AMER MATH SOC.SER B}, journal = {PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY SERIES B}, volume = {9}, unique-id = {33078387}, abstract = {For a compact set A ⊂ R d A \subset \mathbb {R}^d and an integer k ≥ 1 k\ge 1 , let us denote by A [ k ] = { a 1 + ⋯ + a k : a 1 , … , a k ∈ A } = ∑ i = 1 k A \begin{equation*} A[k] = \left \{a_1+\cdots +a_k: a_1, \ldots , a_k\in A\right \}=\sum _{i=1}^k A \end{equation*} the Minkowski sum of k k copies of A A . A theorem of Shapley, Folkmann and Starr (1969) states that 1 k A [ k ] \frac {1}{k}A[k] converges to the convex hull of A A in Hausdorff distance as k k tends to infinity. Bobkov, Madiman and Wang [ Concentration, functional inequalities and isoperimetry , Amer. Math. Soc., Providence, RI, 2011] conjectured that the volume of 1 k A [ k ] \frac {1}{k}A[k] is nondecreasing in k k , or in other words, in terms of the volume deficit between the convex hull of A A and 1 k A [ k ] \frac {1}{k}A[k] , this convergence is monotone. It was proved by Fradelizi, Madiman, Marsiglietti and Zvavitch [C. R. Math. Acad. Sci. Paris 354 (2016), pp. 185–189] that this conjecture holds true if d = 1 d=1 but fails for any d ≥ 12 d \geq 12 . In this paper we show that the conjecture is true for any star-shaped set A ⊂ R d A \subset \mathbb {R}^d for d = 2 d=2 and d = 3 d=3 and also for arbitrary dimensions d ≥ 4 d \ge 4 under the condition k ≥ ( d − 1 ) ( d − 2 ) k \ge (d-1)(d-2) . In addition, we investigate the conjecture for connected sets and present a counterexample to a generalization of the conjecture to the Minkowski sum of possibly distinct sets in R d \mathbb {R}^d , for any d ≥ 7 d \geq 7 .}, year = {2022}, eissn = {2330-1511}, pages = {358-372}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32528369, title = {The optimization process leading to the tessellation of the first geodesic dome structure, the first Planetarium of Jena}, url = {https://m2.mtmt.hu/api/publication/32528369}, author = {Gáspár, Orsolya}, doi = {10.1177/09560599211064110}, journal-iso = {INT J SPACE STRUCT}, journal = {INTERNATIONAL JOURNAL OF SPACE STRUCTURES}, volume = {37}, unique-id = {32528369}, issn = {0956-0599}, year = {2022}, pages = {49-64} } @article{MTMT:32613562, title = {On the convex hull and homothetic convex hull functions of a convex body}, url = {https://m2.mtmt.hu/api/publication/32613562}, author = {G. Horváth, Ákos and Lángi, Zsolt}, doi = {10.1007/s10711-022-00673-y}, journal-iso = {GEOMETRIAE DEDICATA}, journal = {GEOMETRIAE DEDICATA}, volume = {216}, unique-id = {32613562}, issn = {0046-5755}, abstract = {The aim of this note is to investigate the properties of the convex hull and the homothetic convex hull functions of a convex body K in Euclidean n-space, defined as the volume of the union of K and one of its translates, and the volume of K and a translate of a homothetic copy of K, respectively, as functions of the translation vector. In particular, we prove that the convex hull function of the body K does not determine K. Furthermore, we prove the equivalence of the polar projection body problem raised by Petty, and a conjecture of G.Horváth and Lángi about translative constant volume property of convex bodies. We give a short proof of some theorems of Jerónimo-Castro about the homothetic convex hull function, and prove a homothetic variant of the translative constant volume property conjecture for 3-dimensional convex polyhedra. We also apply our results to describe the properties of the illumination bodies of convex bodies.}, year = {2022}, eissn = {1572-9168}, orcid-numbers = {G. Horváth, Ákos/0000-0003-2371-4818; Lángi, Zsolt/0000-0002-5999-5343} } @misc{MTMT:34491158, title = {Finding Nervi – On-site precasting in the Hungarian industrial architecture. Lecture at: "Cold War Interactions: Architectural Exchange Between Italy and the Socialist East" conference and workshop, curated by Alessandro De Magistris, Federico Deambrosis, Ákos Moravánszky, Luca Skansi – Politecnico di Milano,}, url = {https://m2.mtmt.hu/api/publication/34491158}, author = {Haba, Péter and Gáspár, Orsolya}, unique-id = {34491158}, year = {2022} } @CONFERENCE{MTMT:33096462, title = {Improving the incompressibility condition of the explicit SPH method using the control theory}, url = {https://m2.mtmt.hu/api/publication/33096462}, author = {Havasi-Tóth, Balázs}, booktitle = {CMFF’22 Workshop on " Coupling techniques in multiscale atmospheric models: Microphysics, local scale simulations, PBL structureels"}, unique-id = {33096462}, year = {2022}, pages = {522-528} } @article{MTMT:32604626, title = {The effect of wind on historical timber towers analyzed by plastic limit analysis in the focus of a collapse}, url = {https://m2.mtmt.hu/api/publication/32604626}, author = {Hegyi, Dezső and Armuth, Miklós and Halmos, Balázs and Marótzy, Katalin}, doi = {10.1016/j.engfailanal.2021.105852}, journal-iso = {ENG FAIL ANAL}, journal = {ENGINEERING FAILURE ANALYSIS}, volume = {134}, unique-id = {32604626}, issn = {1350-6307}, abstract = {Climate change severely impacts the architectural heritage. Old buildings may have survived many large storms and heavy snows in the past, but extremes have increased recently. Meanwhile, the condition of historical structures gradually degrades even if they have had regular maintenance. Church towers are strongly affected: they are subject to increased wind compared to the other parts of the building. They are in a high location and gain less attention because of their out-of-the-way position. On 17th September 2017, a massive storm in the Banat region, Romania, caused several church towers to collapse: the towers of Toager, Remetea Mare, Donceni and Ghilad fell down to pieces that day. The collapse of the tower of Dumbrava was one of the buildings involved, this study aims to clarify whether the poor condition of the building, or the flaw of the original design was the main reason for the failure in this village. The structural analysis of such historical timber structures can be problematic as the weak joints of the structure limit the load-bearing capacitance in an exceptionally low level if the traditional elastic analysis is used. The present paper points out that the plastic limit analysis can give a more realistic breaking load level for the high order statically indeterminate carpenter roofs.}, year = {2022}, eissn = {1873-1961} } @book{MTMT:33072765, title = {Különleges tartószerkezetek}, url = {https://m2.mtmt.hu/api/publication/33072765}, isbn = {9786155445903}, author = {Hegyi, Dezső and Gáspár, Orsolya and Fehér, Eszter}, publisher = {TERC Szakkönyvkiadó}, unique-id = {33072765}, year = {2022} } @article{MTMT:32541127, title = {Extremal convex polygons inscribed in a given convex polygon}, url = {https://m2.mtmt.hu/api/publication/32541127}, author = {Ködmön, Csenge Lili and Lángi, Zsolt}, doi = {10.1016/j.comgeo.2021.101844}, journal-iso = {COMP GEOM-THEOR APPL}, journal = {COMPUTATIONAL GEOMETRY-THEORY AND APPLICATIONS}, volume = {102}, unique-id = {32541127}, issn = {0925-7721}, abstract = {A convex polygon Q is inscribed in a convex polygon P if every side of P contains at least one vertex of Q. We present algorithms for finding a minimum area and a minimum perimeter convex polygon inscribed in any given convex n-gon in O(n) and O(n(3)) time, respectively. We also investigate other variants of this problem.}, year = {2022}, eissn = {1879-081X}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32658376, title = {The Effect of Connecting Bridges on Vortex-induced Vibration of Skyscrapers}, url = {https://m2.mtmt.hu/api/publication/32658376}, author = {Köhserli, Mehmet and Várkonyi, Péter László}, doi = {10.1556/096.2021.00019}, journal-iso = {ÉPÍTÉS-ÉPÍTÉSZETTUDOMÁNY}, journal = {ÉPÍTÉS-ÉPÍTÉSZETTUDOMÁNY}, volume = {50}, unique-id = {32658376}, issn = {0013-9661}, year = {2022}, eissn = {1588-2764}, pages = {1-16} } @article{MTMT:32749811, title = {A solution to some problems of Conway and Guy on monostable polyhedra}, url = {https://m2.mtmt.hu/api/publication/32749811}, author = {Lángi, Zsolt}, doi = {10.1112/blms.12579}, journal-iso = {B LOND MATH SOC}, journal = {BULLETIN OF THE LONDON MATHEMATICAL SOCIETY}, volume = {54}, unique-id = {32749811}, issn = {0024-6093}, abstract = {A convex polyhedron is called monostable if it can rest in stable position only on one of its faces. The aim of this paper is to investigate three questions of Conway, regarding monostable polyhedra, which first appeared in a 1969 paper of Goldberg and Guy. In this note, we answer two of these problems and make a conjecture about the third one. The main tool of our proof is a general theorem describing approximations of smooth convex bodies by convex polyhedra in terms of their static equilibrium points. As another application of this theorem, we prove the existence of a convex polyhedron with only one stable and one unstable point.}, keywords = {EQUILIBRIA; BODIES; EVERY POINT}, year = {2022}, eissn = {1469-2120}, pages = {501-516}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32729942, title = {An isoperimetric problem for three-dimensional parallelohedra}, url = {https://m2.mtmt.hu/api/publication/32729942}, author = {Lángi, Zsolt}, doi = {10.2140/pjm.2022.316.169}, journal-iso = {PAC J MATH}, journal = {PACIFIC JOURNAL OF MATHEMATICS}, volume = {316}, unique-id = {32729942}, issn = {0030-8730}, abstract = {The aim of this note is to investigate isoperimetric-type problems for 3-dimensional parallelohedra; that is, for convex polyhedra whose translates tile the 3-dimensional Euclidean space. Our main result states that among 3-dimensional parallelohedra with unit volume, the one with minimal mean width is the regular truncated octahedron.}, year = {2022}, eissn = {1945-5844}, pages = {169-181}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:34174919, title = {Pebbles, graphs and equilibria: Higher order shape descriptors for sedimentary particles}, url = {https://m2.mtmt.hu/api/publication/34174919}, author = {Ludmány, Balázs and Domokos, Gábor}, doi = {10.1556/24.2023.00135}, journal-iso = {CENT EUR GEOL}, journal = {CENTRAL EUROPEAN GEOLOGY}, volume = {65}, unique-id = {34174919}, issn = {1788-2281}, abstract = {While three-dimensional measurement technology is spreading fast, its meaningful application to sedimentary geology still lacks content. Classical shape descriptors (such as axis ratios, circularity of projection) were not inherently three-dimensional, because no such technology existed. Recently a new class of three-dimensional descriptors, collectively referred to as mechanical descriptors, has been introduced and applied for a broad range of sedimentary particles. First-order mechanical descriptors (registered for each pebble as a pair {S, U} of integers), refer to the respective numbers of stable and unstable static equilibria and can be reliably detected by hand experiments. However, they have limited ability of distinction, as the majority of coastal pebbles fall into primary class . Higher-order mechanical descriptors offer a more refined distinction. However, for the extraction of these descriptors (registered as graphs for each pebble), hand measurements are not an option and even computer-based extraction from 3D scans offers a formidable challenge. Here we not only describe and implement an algorithm to perform this task, but also apply it to a collection of 271 pebbles with various lithologies, illustrating that the application of higher-order descriptors is a viable option for geologists. We also show that the so-far uncharted connection between the two known secondary descriptors, the so-called Morse–Smale graph and the Reeb-graph, can be established via a third order descriptor which we call the master graph.}, year = {2022}, eissn = {1789-3348}, pages = {158-177}, orcid-numbers = {Ludmány, Balázs/0000-0001-5373-7610} } @inproceedings{MTMT:33089405, title = {A numerical study of the cracking pattern of reinforced concrete rings under hydrostatic pressure}, url = {https://m2.mtmt.hu/api/publication/33089405}, author = {Michel, Sébastien and Sipos, András Árpád}, booktitle = {Proceedings of the 14th fib International PhD Symposium in Civil Engineering}, unique-id = {33089405}, year = {2022}, pages = {361-367}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:32795154, title = {On the cracking patterns of brittle rings with elastic radial support under hydrostatic pressure}, url = {https://m2.mtmt.hu/api/publication/32795154}, author = {Michel, Sébastien and Sipos, András Árpád}, doi = {10.1007/s11012-022-01523-7}, journal-iso = {MECCANICA}, journal = {MECCANICA}, volume = {57}, unique-id = {32795154}, issn = {0025-6455}, year = {2022}, eissn = {1572-9648}, pages = {1639-1656}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:33608718, title = {The role of the particle aspect ratio in the discharge of a narrow silo}, url = {https://m2.mtmt.hu/api/publication/33608718}, author = {Pongó, Tivadar and Fan, Bo and Hernández-Delfin, D. and Török, János and Stannarius, R. and Hidalgo, R.C. and Börzsönyi, Tamás}, doi = {10.1088/1367-2630/ac9923}, journal-iso = {NEW J PHYS}, journal = {NEW JOURNAL OF PHYSICS}, volume = {24}, unique-id = {33608718}, issn = {1367-2630}, year = {2022}, eissn = {1367-2630} } @article{MTMT:33133343, title = {Reducing data dimension boosts neural network-based stage-specific malaria detection}, url = {https://m2.mtmt.hu/api/publication/33133343}, author = {Preißinger, Katharina and Kellermayer, Miklós and Vértessy, Beáta (Grolmuszné) and Kézsmárki, István and Török, János}, doi = {10.1038/s41598-022-19601-x}, journal-iso = {SCI REP}, journal = {SCIENTIFIC REPORTS}, volume = {12}, unique-id = {33133343}, issn = {2045-2322}, abstract = {Although malaria has been known for more than 4 thousand years 1 , it still imposes a global burden with approx. 240 million annual cases 2 . Improvement in diagnostic techniques is a prerequisite for its global elimination. Despite its main limitations, being time-consuming and subjective, light microscopy on Giemsa-stained blood smears is still the gold-standard diagnostic method used worldwide. Autonomous computer assisted recognition of malaria infected red blood cells (RBCs) using neural networks (NNs) has the potential to overcome these deficiencies, if a fast, high-accuracy detection can be achieved using low computational power and limited sets of microscopy images for training the NN. Here, we report on a novel NN-based scheme that is capable of the high-speed classification of RBCs into four categories—healthy ones and three classes of infected ones according to the parasite age—with an accuracy as high as 98%. Importantly, we observe that a smart reduction of data dimension, using characteristic one-dimensional cross-sections of the RBC images, not only speeds up the classification but also significantly improves its performance with respect to the usual two-dimensional NN schemes. Via comparative studies on RBC images recorded by two additional techniques, fluorescence and atomic force microscopy, we demonstrate that our method is universally applicable for different types of microscopy images. This robustness against imaging platform-specific features is crucial for diagnostic applications. Our approach for the reduction of data dimension could be straightforwardly generalised for the classification of different parasites, cells and other types of objects.}, year = {2022}, eissn = {2045-2322}, orcid-numbers = {Kellermayer, Miklós/0000-0002-5553-6553} } @article{MTMT:32623795, title = {A unified morphoelastic rod model with application to growth-induced coiling, waving, and skewing of plant roots}, url = {https://m2.mtmt.hu/api/publication/32623795}, author = {Sipos, András Árpád and Várkonyi, Péter László}, doi = {10.1016/j.jmps.2022.104789}, journal-iso = {J MECH PHYS SOLIDS}, journal = {JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS}, volume = {160}, unique-id = {32623795}, issn = {0022-5096}, abstract = {The shapes of roots exhibit distinctive patterns, which attracted significant attempts at an explanation. We develop a geometrically exact, elastic, three-dimensional morphoelastic rod model of root elongation coupled with control mechanisms representing circumnutation, gravitropism, and thigmotropism. Possible forms of the evolution equations for the intrinsic curvature of the rod, representing these control mechanisms are discussed. By specifying the evolution rules of intrinsic curvatures, the model boils down to a sequential solution of two-point boundary value problems in order to compute the evolving root shape. We simulate root growth on hard soil surfaces with different angles of inclination. Systematic computations show that the morphology is predominantly determined by the model parameters associated with the control mechanisms and by the angle of inclination. Predictions of the new model recover experimentally observed root coiling, waving, and skewing of Arabidopsis thaliana. Our results suggest that the primary mechanism behind root coiling, waving, and skewing is the interplay between circumnutation and gravitropism as slope angle is varied. Thigmotropism has a moderate effect on the emerging shapes.}, year = {2022}, eissn = {1873-4782}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @inproceedings{MTMT:33089425, title = {Experimental study of crack propagation in a brittle hemispherical dome with two pre-existing cracks}, url = {https://m2.mtmt.hu/api/publication/33089425}, author = {Cao, Siwen and Sipos, András Árpád}, booktitle = {Proceedings of the 14th fib International PhD Symposium in Civil Engineering}, unique-id = {33089425}, year = {2022}, pages = {589-596}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @inproceedings{MTMT:33282346, title = {Effect of load path bifurcation on the behavior of reinforced concrete beams}, url = {https://m2.mtmt.hu/api/publication/33282346}, author = {Ther, Péter Pál and Sajtos, István}, booktitle = {Proceedings of the 14th fib International PhD Symposium in Civil Engineering}, unique-id = {33282346}, abstract = {Practical experience shows that the final failure mode of RC beams is asymmetric even in a symmetric experimental setup. This is due to the strain-softening behavior of concrete, which leads to the bifurca-tion of the symmetrical load path. The paper aims to analyze the effect of the failure mode of RC beams without shear reinforcement on the load-bearing capacity and deformational ability (i.e. displacement and rotation). We used ATENA, a nonlinear finite element software to examine the effect of beam size, reinforcement ratio, and fracture energy on the failure mode, load-bearing capacity, and deformational ability of RC beams. The paper also compares experimental and numerical results and explains how the numerical model-ling technique may lead to incorrect results.}, year = {2022}, pages = {97-104} } @inproceedings{MTMT:33834348, title = {From swinging cables to adaptive funicular structures in architecture}, url = {https://m2.mtmt.hu/api/publication/33834348}, author = {Várkonyi, Péter László and Guerra Riaño, Andres Felipe}, booktitle = {IEEE 20th Jubilee International Symposium on Intelligent Systems and Informatics (SISY 2022)}, doi = {10.1109/SISY56759.2022.10036184}, unique-id = {33834348}, year = {2022}, pages = {169-174} } @article{MTMT:32606864, title = {Rigid impacts of three-dimensional rocking structures}, url = {https://m2.mtmt.hu/api/publication/32606864}, author = {Várkonyi, Péter László and Kocsis, Marton and Ther, Tamás}, doi = {10.1007/s11071-021-06934-x}, journal-iso = {NONLINEAR DYNAM}, journal = {NONLINEAR DYNAMICS}, volume = {107}, unique-id = {32606864}, issn = {0924-090X}, abstract = {Studies of rocking motion aim to explain the remarkable earthquake resistance of rocking structures. State-of-the-art assessment methods are mostly based on planar models, despite ongoing efforts to understand the significance of three-dimensionality. Impacts are essential components of rocking motion. We present experimental measurements of free-rocking blocks on a rigid surface, focusing on extreme sensitivity of impacts to geometric imperfections, unpredictability, and the emergence of three-dimensional motion via spontaneous symmetry breaking. These results inspire the development of new impact models of three-dimensional facet and edge impacts of polyhedral objects. Our model is a natural generalization of existing planar models based on the seminal work of George W. Housner. Model parameters are estimated empirically for rectangular blocks. Finally, new perspectives in earthquake assessment of rocking structures are discussed.}, keywords = {MODEL; BEHAVIOR; DYNAMICS; STABILITY; EXCITATION; COLUMNS; Engineering, Mechanical; Masonry arches; rocking block; 3D rocking}, year = {2022}, eissn = {1573-269X}, pages = {1839-1858} } @article{MTMT:32872704, title = {Corrigendum to “On the admissible dualities in Maxwell’s reciprocal construction” [Int. J. Solids Struct. 171 (2019) pages 10–16]}, url = {https://m2.mtmt.hu/api/publication/32872704}, author = {Baranyai, Tamás}, doi = {10.1016/j.ijsolstr.2021.111058}, journal-iso = {INT J SOLIDS STRUCT}, journal = {INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, volume = {225}, unique-id = {32872704}, issn = {0020-7683}, year = {2021}, eissn = {1879-2146} } @CONFERENCE{MTMT:32735565, title = {The force as a function: Towards analytical graphic statics for spatial structures}, url = {https://m2.mtmt.hu/api/publication/32735565}, author = {Baranyai, Tamás}, booktitle = {IASS 2020/21 Surrey Symposium}, unique-id = {32735565}, year = {2021}, pages = {1637-1646} } @article{MTMT:32033263, title = {Analytical graphic statics}, url = {https://m2.mtmt.hu/api/publication/32033263}, author = {Baranyai, Tamás}, doi = {10.1177/09560599211001651}, journal-iso = {INT J SPACE STRUCT}, journal = {INTERNATIONAL JOURNAL OF SPACE STRUCTURES}, volume = {36}, unique-id = {32033263}, issn = {0956-0599}, year = {2021}, pages = {117-126} } @article{MTMT:32133519, title = {Blind competition on the numerical simulation of steel‐fiber‐reinforced concrete beams failing in shear}, url = {https://m2.mtmt.hu/api/publication/32133519}, author = {Barros, Joaquim and Sanz, Beatriz and Kabele, Petr and Yu, Rena C. and Meschke, Günther and Planas, Jaime and Cunha, Vitor and Caggiano, Antonio and Ozyurt, Nilüfer and Gouveia, Ventura and Bos, Ab and Poveda, Elisa and Gal, Erez and Cervenka, Jan and Neu, Gerrit E. and Rossi, Pierre and Dias‐da‐Costa, Daniel and Juhász, Károly Péter and Cendon, David and Ruiz, Gonzalo and Valente, Tiago}, doi = {10.1002/suco.202000345}, journal-iso = {STRUCT CONCRETE}, journal = {STRUCTURAL CONCRETE}, volume = {22}, unique-id = {32133519}, issn = {1464-4177}, abstract = {Experimental research has shown the extraordinary potential of the addition of short fibers to cement-based materials by improving significantly the behavior of concrete structures for serviceability and ultimate limit states. Software based on the finite element method has been used for the simulation of the material nonlinear behavior of fiber-reinforced concrete (FRC) structures. The applicability of the existing approaches has often been assessed by simulating experimental tests with structural elements, in general of a small scale, where the parameter values of the material constitutive laws are adjusted for the aimed predicting level, which constitutes an inverse technique of arguable utility for structural design practice. For assessing the predictive performance of these approaches, a blind simulation competition was organized. Two twin T-cross section steel FRC beams, flexurally reinforced with steel bars and without conventional shear reinforcement in the critical shear span, were experimentally tested up to failure. Despite the experimental data provided for the definition of the relevant model parameters, inaccuracies on the load capacity, deflection, and strain at peak load attained 40, 113, and 600%, respectively. Inadequate failure modes and highly different results were estimated with the same commercial software, indicating the need for deeper analysis and understanding of the models and influence of their parameters on their predictive performance.}, year = {2021}, eissn = {1751-7648}, pages = {939-967}, orcid-numbers = {Barros, Joaquim/0000-0003-1528-757X} } @article{MTMT:32036139, title = {Using SDA Model in the Designing Process of Fiber-Reinforced Concrete Beams}, url = {https://m2.mtmt.hu/api/publication/32036139}, author = {Erdélyiné Tóth, Mária and Pluzsik, Anikó}, doi = {10.1061/(ASCE)MT.1943-5533.0003803}, journal-iso = {J MATER CIVIL ENG}, journal = {JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, volume = {33}, unique-id = {32036139}, issn = {0899-1561}, year = {2021}, eissn = {1943-5533}, pages = {04021191}, orcid-numbers = {Erdélyiné Tóth, Mária/0000-0003-3911-7110} } @article{MTMT:32476286, title = {Tracking the critical points of curves evolving under planar curvature flows}, url = {https://m2.mtmt.hu/api/publication/32476286}, author = {Fehér, Eszter and Domokos, Gábor and Krauskopf, Bernd}, doi = {10.3934/jcd.2021017}, journal-iso = {J COMPUT DYNAM}, journal = {JOURNAL OF COMPUTATIONAL DYNAMICS}, volume = {8}, unique-id = {32476286}, issn = {2158-2491}, year = {2021}, eissn = {2158-2505}, pages = {447-494} } @article{MTMT:32162755, title = {Hexagon tilings of the plane that are not edge-to-edge}, url = {https://m2.mtmt.hu/api/publication/32162755}, author = {Frettlöh, D. and Glazyrin, A. and Lángi, Zsolt}, doi = {10.1007/s10474-021-01155-5}, journal-iso = {ACTA MATH HUNG}, journal = {ACTA MATHEMATICA HUNGARICA}, volume = {164}, unique-id = {32162755}, issn = {0236-5294}, abstract = {An irregular vertex in a tiling by polygons is a vertex of one tile and belongs to the interior of an edge of another tile. In this paper we show that for any integer k >= 3, there exists a normal tiling of the Euclidean plane by convex hexagons of unit area with exactly k irregular vertices. Using the same approach we show that there are normal edge-to-edge tilings of the plane by hexagons of unit area and exactly k many n-gons (n > 6) of unit area. A result of Akopyan yields an upper bound for k depending on the maximal diameter and minimum area of the tiles. Our result complements this with a lower bound for the extremal case, thus showing that Akopyan's bound is asymptotically tight.}, year = {2021}, eissn = {1588-2632}, pages = {341-349}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:32274219, title = {Friction as a geometric constraint on stereotomy in the minimum thickness analysis of circular and elliptical masonry arches}, url = {https://m2.mtmt.hu/api/publication/32274219}, author = {Gáspár, Orsolya and Sajtos, István and Sipos, András Árpád}, doi = {10.1016/j.ijsolstr.2021.111056}, journal-iso = {INT J SOLIDS STRUCT}, journal = {INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, volume = {225}, unique-id = {32274219}, issn = {0020-7683}, abstract = {Friction is much needed for the equilibrium of masonry arches as it transfers load between the voussoirs. In this paper, applying an analytical formulation of the problem, the angle of friction as a geometric constraint on the stereotomy (bricklaying pattern) is investigated to find the possible range of minimum thickness values of circular and elliptical masonry arches under static loads based on the lower bound theorem of limit state analysis. The Heymanian assumptions regarding material qualities are adopted; however, limited capacity in friction is accounted for. It has been shown earlier that considering stereotomies a-priori unknown, a considerably wide range of minimum thickness values is obtained for fixed loading and global geometry conditions. It is found that a stereotomy constrained by an angle of friction, characteristic of masonry, renders the effect of stereotomy on the minimum thickness value negligible because the range of minimum thickness values is significantly reduced in this case. Hence, the present study ultimately justifies the intuitive assumption of radial stereotomy, widely used in the literature, whenever the safety of masonry arches is studied. (C) 2021 The Author(s). Published by Elsevier Ltd.}, keywords = {Friction; Arches; Masonry-like materials; Stereotomy; Limit analysis, equilibrium problem}, year = {2021}, eissn = {1879-2146}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @inproceedings{MTMT:31847313, title = {Safe estimation of minimum thickness of circular masonry arches considering stereotomy and different rotational failure modes}, url = {https://m2.mtmt.hu/api/publication/31847313}, author = {Gáspár, Orsolya and Sajtos, István and Sipos, András Árpád}, booktitle = {12th International Conference on Structural Analysis of Historical Constructions, SAHC 2021}, doi = {10.23967/sahc.2021.216}, unique-id = {31847313}, abstract = {Limit state analysis of masonry arches sets to assess the safety of the structure by determining the minimum thickness that just contains a thrust line. Based on the Heymanian assumptions regarding material qualities and the equilibrium approach to the static theorem it has been explicitly proven for semi-circular arches that both the thrust line and the resulting minimum thickness value is subject to stereotomy (brick or stone laying pattern), while present study demonstrates, that the latter statement holds for pointed-circular arches as well. This is not straightforward, since the number- and arrangement of the hinges at limit state vary subject to the geometry in case of pointed-circular arches, resulting a more complex problem. It is also explicitly shown, that stereotomy might also affect the corresponding (rotational) failure mode (for certain arch geometries). Stereotomy of an existing structure is not always known, hence it is relevant to search for a stereotomy related bounding value of minimum thickness for each of the various failure modes. The potential of the envelope of resultants as a thrust line (resulting from vertical stereotomy) leading to bounding value minimum thicknesses is discussed: as shown elsewhere it bounds the family of thrust lines, hence leads to an upper bound value of minimum thickness in case of semi-circular arches. It is demonstrated however, that this cannot be generalized for other rotational failure modes which occur for circular-pointed arches. The envelope of resultants does not necessarily lead to a bounding value of minimum thickness, and even if it does, it can be either an upper or a lower bound. However, it is found that the range of minimum thickness values is bounded in all possible failure mode types. The necessary conditions are provided for each.}, year = {2021}, pages = {2229-2239}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @CONFERENCE{MTMT:31847302, title = {Bauersfeld’s concept for the subdivision of the first built geodesic dome structure}, url = {https://m2.mtmt.hu/api/publication/31847302}, author = {Gáspár, Orsolya}, booktitle = {IASS 2020/21 Surrey Symposium}, unique-id = {31847302}, abstract = {The metal lattice shell reinforcement of the first Planetarium in Jena, designed by Walther Bauersfeld, chief engineer of the Carl Zeiss AG in 1922 is considered the world’s first geodesic dome. In this study we demonstrate that the tessellation of the dome was much more delicate than previous studies suggested. As the dome was meant to be a temporary structure it was demolished shortly after its erection. Sources on the original design had been considered scarce: a few original pictures taken during construction and Bauersfeld’s handwritten notes, which are kept in the Zeiss Archives. These serve as primary resources for the present research. We show below that the unanimous assumption of previous studies, that the tessellation is identical to Buckminster Fuller’s icosahedral subdivision is neither supported by the existing documents and nor it is likely to be true. We present the results of a series of 3D reconstructions considering (a) Fuller’s icosahedral subdivision, (b) side-bisection and (c) an almost-equal area triangulation of the spherical surface found in Bauersfeld’s notes. These are compared to the existing photographs with the first resulting worst and the last resulting best match. It is also pointed out that the equal-area triangulation results a very smooth grid and contains relatively few different bars. This underlines the extraordinary skills of Bauersfeld as an engineer – who invented this tessellation 30-50 years prior to any theoretical studies on the optimal tessellation of geodesic domes.}, year = {2021}, pages = {1-11} } @article{MTMT:31770965, title = {Numerical stability analysis of arch-supported membrane roofs}, url = {https://m2.mtmt.hu/api/publication/31770965}, author = {Hegyi, Dezső}, doi = {10.1016/j.istruc.2020.11.025}, journal-iso = {STRUCTURES}, journal = {STRUCTURES}, volume = {29}, unique-id = {31770965}, issn = {2352-0124}, year = {2021}, eissn = {2352-0124}, pages = {785-795} } @CONFERENCE{MTMT:32063628, title = {Lyukacsos (anizotrop) téglaelem laboratóriumi és numerikus vizsgálata}, url = {https://m2.mtmt.hu/api/publication/32063628}, author = {Hortobágyi, Tamás and Roszevák, Zsolt and Haris, István and Sajtos, István}, booktitle = {XXV. Nemzetközi Építéstudományi Online Konferencia – ÉPKO}, unique-id = {32063628}, year = {2021}, pages = {72-79}, orcid-numbers = {Haris, István/0000-0002-4669-8606} } @article{MTMT:32042382, title = {A proposed evaluation method for three-point beam tests of fiber-reinforced concrete}, url = {https://m2.mtmt.hu/api/publication/32042382}, author = {Juhász, Károly Péter}, doi = {10.1520/JTE20190782}, journal-iso = {J TEST EVAL}, journal = {JOURNAL OF TESTING AND EVALUATION}, volume = {49}, unique-id = {32042382}, issn = {0090-3973}, abstract = {The characteristic values of the material parameters used for structural design are usually determined from the mean and standard deviation of the material test results, and the design values are calculated from the characteristic values using the appropriate safety factor. However, if the standard deviation of the test data is high, the characteristic value is expected to be significantly lower than the mean value. In the case of fiber-reinforced concrete (FRC), the coefficient of variation is usually high, which can be attributed to the relatively small size of the specimen and the random location of the fibers. To overcome this limitation, this paper proposes a method that takes into account the number and location of the fibers when estimating the postcrack performance for a cracked cross section in a three-point notched bending beam tests. Test results of steel- and macrosynthetic FRC were evaluated using both the RILEM recommendations and the proposed method and are finally compared. Although the proposed method is more complex and the evaluation requires more effort than the existing method, it provides more repeatable material parameters, which exhibited a higher characteristic result. Copyright © 2020 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959}, year = {2021}, eissn = {1945-7553}, pages = {3838-3858} } @article{MTMT:31940771, title = {An elastic phenomenological material law of technical textile with a nonlinear shear behaviour}, url = {https://m2.mtmt.hu/api/publication/31940771}, author = {Karádi, Dániel Tamás and Sipos, András Árpád and Halász, Marianna and Hliva, Viktor and Hegyi, Dezső}, doi = {10.1177/07316844211005842}, journal-iso = {J REINF PLAST COMP}, journal = {JOURNAL OF REINFORCED PLASTICS AND COMPOSITES}, volume = {40}, unique-id = {31940771}, issn = {0731-6844}, abstract = {In technical textile engineering, macro-level phenomenological modelling effectively describes the material's highly nonlinear behaviour. However, existing material laws concentrate on the normal stiffness in the orthotropic yarns and simplify the shear effect because of the two orders of magnitude difference between shear and normal stiffness. This article introduces an improved phenomenological model that includes nonlinear shear behaviour, and it determines the material parameters with a previously applied data fitting method for exponential functions. The nonlinear shear behaviour is valid for the elastic state, that is, at the service level of the loads. Time-dependent, cyclic loading or plastic behaviour is not considered.}, keywords = {Shear modulus; technical textiles; uniaxial test; nonlinear constitutive law}, year = {2021}, eissn = {1530-7964}, pages = {759-769}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165; Halász, Marianna/0000-0002-0289-8817; Hliva, Viktor/0000-0002-1286-5787; Hegyi, Dezső/0000-0002-1543-0682} } @article{MTMT:32592511, title = {An Extensive Review on the Viscoelastic-plastic and Fractural Mechanical Behaviour of ETFE Membranes}, url = {https://m2.mtmt.hu/api/publication/32592511}, author = {Karádi, Dániel Tamás and Hegyi, Dezső}, doi = {10.3311/PPar.18403}, journal-iso = {PERIOD POLYTECH ARCHITECT}, journal = {PERIODICA POLYTECHNICA ARCHITECTURE}, volume = {52}, unique-id = {32592511}, issn = {0324-590X}, year = {2021}, eissn = {1789-3437}, pages = {121-134} } @article{MTMT:32214116, title = {Soft impact of an elongated elasto-plastic missile}, url = {https://m2.mtmt.hu/api/publication/32214116}, author = {Károlyi, György and Sipos, András Árpád}, doi = {10.1016/j.ijmecsci.2021.106804}, journal-iso = {INT J MECH SCI}, journal = {INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES}, volume = {212}, unique-id = {32214116}, issn = {0020-7403}, abstract = {Motivated by the grave consequences of an aircraft impact into robust engineering structures like nuclear power plants, we investigate the time-dependent reaction force during the impact of a crushing, elongated elasto-plastic missile into a robust elastic target. We derive a set of partial differential equations on a time-dependent domain to describe the impact. The simplest case of a homogeneous, cylindrical aircraft fuselage impacting a rigid target is solved analytically by using conformal mapping. After developing a numerical scheme for the case of an elastic target, we find that a simple dimensionless number, the damage potential, gives an accurate prediction of the impact force. The peak reaction force during the impact is found to exceed the initial impact force by up to 20%; hence the often applied strategy to estimate the peak force as the initial impact force is not a conservative approach. This effect is due to a resonant vibration in both the missile and the target. Predicted and computed parameters at which this counter-intuitive, resonance-like behavior occurs are shown to agree well.}, year = {2021}, eissn = {1879-2162}, orcid-numbers = {Károlyi, György/0000-0002-1021-9554; Sipos, András Árpád/0000-0003-0440-2165} } @inproceedings{MTMT:32924413, title = {Vibration of structurally connected high-rise buildings under wind force}, url = {https://m2.mtmt.hu/api/publication/32924413}, author = {Köhserli, Mehmet and Várkonyi, Péter László}, booktitle = {IABSE Congress Ghent 2021}, unique-id = {32924413}, abstract = {Cities are organized around various underlying networks but building structures do not follow this trend. The isolation of structural systems causes difficulties in the case of tall structures. We investigate the possibility of improving structural behaviour by organizing buildings into urban-scale structural networks, with focus on vortex-induced vibration. We review our recent work, in which randomly generated collections of high-rise buildings were examined by numerical simulation using a conceptual model of the network composed of springs and point masses. Here we examine the behaviour of a realistic collection of buildings, generated by considering the existing building stock and urban fabric of Midtown Manhattan. The new simulation results suggest that connections among the buildings would enable the application of significantly softer bracing systems. This finding suggests that urban-scale structural networks is a promising direction of urban development. © 2021 IABSE Congress, Ghent 2021: Structural Engineering for Future Societal Needs. All rights reserved.}, keywords = {NETWORK; NETWORK; Structural design; VIBRATION; VIBRATION; wind; Vortex flow; Urban growth; Vortex-shedding; High-rise buildings; Tall buildings; Structural networks; SLENDERNESS; SLENDERNESS; Urban scale; Vortex shedding; Vortex shedding; Manhattans; Structurally-connected; Manhattan; High rise building; Wind forces}, year = {2021}, pages = {1598-1605} } @article{MTMT:32153529, title = {Centering Koebe polyhedra via Möbius transformations}, url = {https://m2.mtmt.hu/api/publication/32153529}, author = {Lángi, Zsolt}, doi = {10.4171/GGD/596}, journal-iso = {GROUPS GEOMETRY DYNAMICS}, journal = {GROUPS GEOMETRY AND DYNAMICS}, volume = {15}, unique-id = {32153529}, issn = {1661-7207}, abstract = {A variant of the Circle Packing Theorem states that the combinatorial class of any convex polyhedron contains elements, called Koebe polyhedra, midscribed to the unit sphere centered at the origin, and that these representatives are unique up to Möbius transformations of the sphere. Motivated by this result, various papers investigate the problem of centering spherical configurations under Möbius transformations. In particular, Springborn proved that for any discrete point set on the sphere there is a Möbius transformation that maps it into a set whose barycenter is the origin, which implies that the combinatorial class of any convex polyhedron contains an element midsribed to a sphere with the additional property that the barycenter of the points of tangency is the center of the sphere. This result was strengthened by Baden, Krane and Kazhdan who showed that the same idea works for any reasonably nice measure defined on the sphere. The aim of the paper is to show that Springborn’s statement remains true if we replace the barycenter of the tangency points by many other polyhedron centers. The proof is based on the investigation of the topological properties of the integral curves of certain vector fields defined in hyperbolic space. We also show that most centers of Koebe polyhedra cannot be obtained as the center of a suitable measure defined on the sphere.}, year = {2021}, eissn = {1661-7215}, pages = {197-221}, orcid-numbers = {Lángi, Zsolt/0000-0002-5999-5343} } @article{MTMT:31991964, title = {Interacting jammed granular systems}, url = {https://m2.mtmt.hu/api/publication/31991964}, author = {Lévay, Sára and Fischer, D. and Stannarius, R. and Somfai, Ellák and Börzsönyi, Tamás and Brendel, L. and Török, János}, doi = {10.1103/PhysRevE.103.042901}, journal-iso = {PHYSICAL REVIEW E}, journal = {PHYSICAL REVIEW E: COVERING STATISTICAL NONLINEAR BIOLOGICAL AND SOFT MATTER PHYSICS (2016-)}, volume = {103}, unique-id = {31991964}, issn = {2470-0045}, year = {2021}, eissn = {2470-0053}, orcid-numbers = {Lévay, Sára/0000-0001-9549-0046; Somfai, Ellák/0000-0002-2218-8855} } @article{MTMT:31937866, title = {Evolution of shear zones in granular packings under pressure}, url = {https://m2.mtmt.hu/api/publication/31937866}, author = {Madani, Mahnoush and Maleki, Maniya and Török, János and Shaebani, M. Reza}, doi = {10.1039/D0SM01768J}, journal-iso = {SOFT MATTER}, journal = {SOFT MATTER}, volume = {17}, unique-id = {31937866}, issn = {1744-683X}, year = {2021}, eissn = {1744-6848}, pages = {1814-1820}, orcid-numbers = {Maleki, Maniya/0000-0003-1190-0947; Török, János/0000-0002-4275-2396; Shaebani, M. Reza/0000-0001-8587-6949} } @article{MTMT:33708014, title = {Az igazfalvi református templom}, url = {https://m2.mtmt.hu/api/publication/33708014}, author = {Marótzy, Katalin and Halmos, Balázs and Armuth, Miklós and Hegyi, Dezső}, journal-iso = {DOLG ERDÉLYI MÚZ ÉREM- ÉS RÉGISÉGTÁRÁBÓL}, journal = {DOLGOZATOK AZ ERDÉLYI MÚZEUM ÉREM- ÉS RÉGISÉGTÁRÁBÓL}, unique-id = {33708014}, issn = {1842-5089}, year = {2021} } @article{MTMT:32869102, title = {Deep Learning Exploration of Agent-Based Social Network Model Parameters}, url = {https://m2.mtmt.hu/api/publication/32869102}, author = {Murase, Y. and Jo, H.-H. and Török, János and Kertész, J. and Kaski, K.}, doi = {10.3389/fdata.2021.739081}, journal-iso = {FRONT BIG DATA}, journal = {FRONTIERS IN BIG DATA}, volume = {4}, unique-id = {32869102}, abstract = {Interactions between humans give rise to complex social networks that are characterized by heterogeneous degree distribution, weight-topology relation, overlapping community structure, and dynamics of links. Understanding these characteristics of social networks is the primary goal of their research as they constitute scaffolds for various emergent social phenomena from disease spreading to political movements. An appropriate tool for studying them is agent-based modeling, in which nodes, representing individuals, make decisions about creating and deleting links, thus yielding various macroscopic behavioral patterns. Here we focus on studying a generalization of the weighted social network model, being one of the most fundamental agent-based models for describing the formation of social ties and social networks. This generalized weighted social network (GWSN) model incorporates triadic closure, homophilic interactions, and various link termination mechanisms, which have been studied separately in the previous works. Accordingly, the GWSN model has an increased number of input parameters and the model behavior gets excessively complex, making it challenging to clarify the model behavior. We have executed massive simulations with a supercomputer and used the results as the training data for deep neural networks to conduct regression analysis for predicting the properties of the generated networks from the input parameters. The obtained regression model was also used for global sensitivity analysis to identify which parameters are influential or insignificant. We believe that this methodology is applicable for a large class of complex network models, thus opening the way for more realistic quantitative agent-based modeling. © Copyright © 2021 Murase, Jo, Török, Kertész and Kaski.}, keywords = {Sensitivity analysis; Social networks; Agent-based modeling; High-performance computing; Metamodeling; Deep learning}, year = {2021}, eissn = {2624-909X} } @article{MTMT:32218766, title = {Experimental Verification of Stability Theory for a Planar Rigid Body With Two Unilateral Frictional Contacts}, url = {https://m2.mtmt.hu/api/publication/32218766}, author = {Or, Yizhar and Várkonyi, Péter László}, doi = {10.1109/TRO.2021.3064871}, journal-iso = {IEEE T ROBOT}, journal = {IEEE TRANSACTIONS ON ROBOTICS}, volume = {37}, unique-id = {32218766}, issn = {1552-3098}, year = {2021}, eissn = {1941-0468}, pages = {1634-1648} } @article{MTMT:32463947, title = {Curvature flows, scaling laws and the geometry of attrition under impacts}, url = {https://m2.mtmt.hu/api/publication/32463947}, author = {Pál, Gergő and Domokos, Gábor and Kun, Ferenc}, doi = {10.1038/s41598-021-00030-1}, journal-iso = {SCI REP}, journal = {SCIENTIFIC REPORTS}, volume = {11}, unique-id = {32463947}, issn = {2045-2322}, abstract = {Impact induced attrition processes are, beyond being essential models of industrial ore processing, broadly regarded as the key to decipher the provenance of sedimentary particles. Here we establish the first link between microscopic, particle-based models and the mean field theory for these processes. Based on realistic computer simulations of particle-wall collision sequences we first identify the well-known damage and fragmentation energy phases, then we show that the former is split into the abrasion phase with infinite sample lifetime (analogous to Sternberg's Law) at finite asymptotic mass and the cleavage phase with finite sample lifetime, decreasing as a power law of the impact velocity (analogous to Basquin's Law). This splitting establishes the link between mean field models (curvature-driven partial differential equations) and particle-based models: only in the abrasion phase does shape evolution emerging in the latter reproduce with startling accuracy the spatio-temporal patterns (two geometric phases) predicted by the former.}, year = {2021}, eissn = {2045-2322} } @article{MTMT:31919027, title = {Flow in an hourglass: Particle friction and stiffness matter}, url = {https://m2.mtmt.hu/api/publication/31919027}, author = {Pongó, Tivadar and Stiga, Viktória and Török, János and Lévay, Sára and Szabó, Balázs and Stannarius, R. and Hidalgo, R.C. and Börzsönyi, Tamás}, doi = {10.1088/1367-2630/abddf5}, journal-iso = {NEW J PHYS}, journal = {NEW JOURNAL OF PHYSICS}, volume = {23}, unique-id = {31919027}, issn = {1367-2630}, year = {2021}, eissn = {1367-2630}, orcid-numbers = {Lévay, Sára/0000-0001-9549-0046} } @inproceedings{MTMT:32458382, title = {General thurst surface of masonry domes}, url = {https://m2.mtmt.hu/api/publication/32458382}, author = {Sajtos, István and Sipos, András Árpád and Gáspár, Orsolya}, booktitle = {12th International Conference on Structural Analysis of Historical Constructions, SAHC 2021}, doi = {10.23967/sahc.2021.120}, unique-id = {32458382}, abstract = {Masonry domes are shell-like structures with a no-tension type material behavior [1]. The dome geometry, material behavior and the type of the loading define how the dome balances the load. It is known and proved that the dome could balance the load only by forces, without bending moment but cracks may appear since the material does not resist tension. The surface where the balancing forces are acting is called the thrust surface. The paper introduces the idea of the general thrust surface. It is such a balancing surface where the forces are not acting in the tangent plane of the thrust surface and otherwise it is moment free. A method is shown how to find the general thrust surface for a cracked spherical masonry dome. Numerical example illustrates the usefulness and effectiveness of the proposed method to determine the general thrust surface of a spherical dome when radial stereotomy is considered. By the help of the proposed model the safety of the more than 350 years old, cracked dome of Gol Gumbaz, India can be proofed.}, year = {2021}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:32678311, title = {Gravity Governs Shear Localization in Confined Dense Granular Flows}, url = {https://m2.mtmt.hu/api/publication/32678311}, author = {Shaebani, M.R. and Török, János and Maleki, M. and Madani, M. and Harrington, M. and Rice, A. and Losert, W.}, doi = {10.1103/PhysRevLett.127.278003}, journal-iso = {PHYS REV LETT}, journal = {PHYSICAL REVIEW LETTERS}, volume = {127}, unique-id = {32678311}, issn = {0031-9007}, abstract = {The prediction of flow profiles of slowly sheared granular materials is a major geophysical and industrial challenge. Understanding the role of gravity is particularly important for future planetary exploration in varying gravitational environments. Using the principle of minimization of energy dissipation, and combining experiments and variational analysis, we disentangle the contributions of the gravitational acceleration, confining pressure, and layer thickness on shear strain localization induced by moving fault boundaries at the bottom of a granular layer. The flow profile is independent of the gravity for geometries with a free top surface. However, under a confining pressure or if the sheared layer withstands the weight of the upper layers, increasing gravity promotes the transition from closed shear zones buried in the bulk to open ones that intersect the top surface. We show that the center position and width of the shear zone and the axial angular velocity at the top surface follow universal scaling laws when properly scaled by the gravity, applied pressure, and layer thickness. Our finding that the flow profiles lie on a universal master curve opens the possibility to predict the quasistatic shear flow of granular materials in varying gravitational environments.}, year = {2021}, eissn = {1079-7114} } @article{MTMT:31890542, title = {Particle size dynamics in abrading pebble populations}, url = {https://m2.mtmt.hu/api/publication/31890542}, author = {Sipos, András Árpád and Domokos, Gábor and Török, János}, doi = {10.5194/esurf-9-235-2021}, journal-iso = {E SURF DYN}, journal = {EARTH SURFACE DYNAMICS}, volume = {9}, unique-id = {31890542}, issn = {2196-6311}, abstract = {Abrasion of sedimentary particles in fluvial and eolian environments is widely associated with collisions encountered by the particle. Although the physics of abrasion is complex, purely geometric models recover the course of mass and shape evolution of individual particles in low- and middle-energy environments (in the absence of fragmentation) remarkably well. In this paper, we introduce the first model for the collision-driven collective mass evolution of sedimentary particles. The model utilizes results of the individual, geometric abrasion theory as a collision kernel; following techniques adopted in the statistical theory of coagulation and fragmentation, the corresponding Fokker–Planck equation is derived. Our model uncovers a startling fundamental feature of collective particle size dynamics: collisional abrasion may, depending on the energy level, either focus size distributions, thus enhancing the effects of size-selective transport, or it may act in the opposite direction by dispersing the distribution.}, year = {2021}, eissn = {2196-632X}, pages = {235-251}, orcid-numbers = {Sipos, András Árpád/0000-0003-0440-2165} } @article{MTMT:32114285, title = {The cause of damage and failure of the Mud-brick vault of the Khan in New-Gourna}, url = {https://m2.mtmt.hu/api/publication/32114285}, author = {Szabó, Simon and Kövesdi, Andrea and Vasáros, Zsolt and O. Csicsely, Ágnes Magdolna and Hegyi, Dezső}, doi = {10.1016/j.engfailanal.2021.105567}, journal-iso = {ENG FAIL ANAL}, journal = {ENGINEERING FAILURE ANALYSIS}, volume = {128}, unique-id = {32114285}, issn = {1350-6307}, abstract = {New Gourna, Egypt became an iconic place of mud-brick architecture in the middle of the 20th century as a result of the work of Hassan Fathy. In the dry climate of Egypt, mud-brick is an almost perfect building material, but the change in the environmental circumstances have caused damage to the structures. The present study aims to find the root of the problems to give chance to find suggestions for reliable strengthening. The paper focuses on one of the central buildings of New Gourna, the so-called Khan, designed by Hassan Fathy. The structure of the arcade of the Khan is modeled by advanced Finite Element method to simulate gradual deformation and failure with special attention to recent renovations that seem to have turned the condition of the structures even worse. As there are no experimental tests on the real materials, possible material models were collected for the analysis, and the most feasible result, which fits the visible failure was accepted. According to the analysis, the failure of the structure is caused by the wetting of the mud mortar layer between the limestone elements of the plinth. There were no significant signs of weakness in the foundation. The wetting of the mud mortar in the plinth is caused by the dramatical change in the ground-water level caused by the building of the Aswan High Dam and the dramatic change in the amount of wastewater caused by the increased population in New Gourna.}, year = {2021}, eissn = {1873-1961}, orcid-numbers = {Hegyi, Dezső/0000-0002-1543-0682} } @article{MTMT:32037102, title = {Dynamical similarity of multi-block catenary arches and rocking blocks subjected to horizontal base excitation}, url = {https://m2.mtmt.hu/api/publication/32037102}, author = {Ther, Tamás and Kollár, László Péter}, doi = {10.1007/s11071-021-06415-1}, journal-iso = {NONLINEAR DYNAM}, journal = {NONLINEAR DYNAMICS}, volume = {104}, unique-id = {32037102}, issn = {0924-090X}, abstract = {In this paper, the dynamical similarity of multi-block catenary arches and columns is discussed, which can be used for the simplified design of rocking arches. The basic hypothesis is that the dynamic response of multi-block arches and columns is similar when the shape of the arch follows the thrust line, i.e. it is a catenary arch. It is validated numerically that the responses of slender catenary arches are safe and reliable approximations of those of not slender arches and then that the overturning acceleration (response) spectra of rigid, slender monolithic blocks can be directly applied for catenary arches. The similarity is based on two parameters, on the limit peak ground acceleration (under which the structure will not move at all) and on the frequency parameter (defined by Housner for rigid blocks).}, keywords = {Rigid body; Engineering, Mechanical; Rocking; Multi-block arch; Overturning spectra}, year = {2021}, eissn = {1573-269X}, pages = {2099-2116}, orcid-numbers = {Kollár, László Péter/0000-0001-9313-2296} }